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Unit-I : Reproduction, INTRODUCTION, Reproduction is the ability of living organisms to produce a new generation of living organisms similar to themselves. It is one of the fundamental characteristics of life. Reproduction provides group immortality by replacing the dead individuals with new ones. Reproduction is aimed at increasing population. It is broadly classified as asexual and sexual reproduction. Human beings reproduce sexually and are viviparous. The process of reproduction in human beings is mentioned at page no. 3., Development biology: all events which changes a zygote into a fully formed animal and therefore contributes to its growth to adulthood and finally to old age and death are referred to as development., Embryonic development: this period is passed in the womb of mother. The, When embryo acquires adult features, it is called foetus. Formation of embryo or foetus is called embryogenesis., Post- embryonic period: the part of life history in an animal from hatching or birth through adulthood to its death is termed post embryonic or postnatal period., Development biology: the study of processes involving orderly changes in structure and physiology of an organism during their life from zygote to death is called development biology., Phases of embryonic development, Embryonic development involves from basic phases in all animals:, Gametogenesis: formation of gametes: male gamete (spermatozoa) and female (ova)., Fertilization: union of male and female gamete to form zygote., Gestation: development events from conception till birth of the young one also termed pregnancy., Cleavage and blastulation: rapid division of the zygote to form a multicellular body of cells called blastomeres., Gastulation: movement of cells to form germ layers., Organogenesis: formation of organs., Parturition: birth of full term young one., Gestation period, Human – 280 days, Rat – 22 days, Dog – 63 days, Cat – 63 days, Goat and sheep – 148 days, Cow – 270 days, Whale – 365 days, Elephant – 641 days., Asexual Reproduction, Production of offspring by a single parent without the formation and fusion of gametes is called asexual reproduction. Asexual reproduction is also called agamogeny or agamogenesis.it is also called as somatogenic reproduction. It involves only mitotic divisions. Asexual reproduction produces identical offspring commonly referred as clone and each individual is called as ramet. The cell , or a part of body which helps in the formation of a new individual by this type of reproduction is called as blastos and this process is called as blastogenesis. Asexual reproduction helps in quick multiplication of organisms. It plays no role in evolution., Types of asexual reproduction, Binary fission: binary fission is the division of the parent into two small, nearly equal-sized daughter individuals. In binary fission nuclear division occurs first followed by cytogenesis. The division occurs by intranuclear mitosis. Example: protozoa, flatworm like planaria. Binary fission is of three types with regard to the plane of division:, (a) Irregular binary fission: it occurs in amoeba. Plane of division of cytoplasm(cytokinesis) is variable but is always at right angle to the elongated dividing nucleus., (b) Longitudinal binary fission: it occurs in flagellates such as Euglena. The cytoplasm splits lengthwise forming two similar daughter individuals., (c) Transverse binary fission: it occurs in ciliates such as paramecium. The cytoplasm divides transversely between two sets of nuclei, forming two dissimilar daughter individual. Paramecium is heterokaryotic and possess two nuclei I,e meganucleus and micronucleus. The meganucleus is vegetative while as the micro nucleus is reproductive., (d) Planaria: planaria (flatworm) divides by transverse binary fission. The worm fixes the posterior part of the body firmly to the substratum and moves the anterior part forward. Due to pull, the middle part is stretched, constricts and finally breaks. The anterior part regenerates posterior part and the posterior part regenerates anterior part. Thus two complete worm are forms., 2. Multiple fission: it is the division of the parent into many small daughter individuals simultaneously., Example: protozoa such as plasmodium and Amoeba., Process: the nucleus of the parent divides a few to many times without division of the cytoplasm. Later, the cytoplasm also divides each part enclosing one nucleus. This produces many daughter individuals from one parent at the same time. Multiple fission shows many variations., (b) Amoeba: in amoeba, the products of multiple fission become individually surrounded by resistant coats, the cyst walls called encystation. The multiple fission here is called sporulation and the encysted products are termed spores. The spore become active during favorable conditions and each cyst hatches into new amoeba. The amoeba may also form cyst wall and on arrival of favorable conditions the amoeba shows multiple fission and form new individuals called as amoebulae or pseudopodiospore., 4. Budding: formation of a daughter individual from a small projection, the bud, arising on the parent body is called budding. Example: protozoa like sponges (scypha) : coelenterates (hydra) : annelid(sylis)etc., Process: the parent body may form a single bud or many buds simultaneously. A bud grows and gradually assumes the form and size of the parent. The bud separates from parent body and grows into an adult while leading an independent life in protozoa. In hydra (coelenterates) the new individuals can live an independent life or form a colony. Each individual of a colony is called zooid., Types : budding is of two types:, External budding: Buds arise from the surface of parents body as in hydra., Internal budding: (Gemmule) Buds are formed within the parent body in fresh water sponges e,g spongilla. These consist of small groups of cells called archaeocytes, enclosed by a resistant protective coat. These are called gemmule. A gemmule germinates into a new sponge under favorable conditions., Fragmentation: It is the breaking of an animal body into two or more pieces, each of which grows into a new individual. It occurs in the flatworms Microstomum. Fragmentation is always accompanied by regeneration., Characteristics of asexual reproduction:, A single parent produces offspring (uniparental)., No gamete formation., Cell division only mitotic., New individual genetically identical to parents., Rapid multiplication., No role in evolution., Sexual Reproduction, It is that type of reproduction that occurs by formation and fusion of gametes., It is the production of offspring usually by two parents, male and female. The four processes involved in sexual reproduction are:, 1. Formation of gametes (Gametogenesis), 2. Fusion of gametes to form zygote (fertilization)., 3. Repeated mitotic division to embryo (embryogenesis)., 4. Growth of embryo to new individual (development)., Example: sexual reproduction occurs in all animals. Some protozoa like amoeba, euglena lack sexual reproduction., Types of sexual reproduction:, 1. Amphigony: it involves complete and permanent fusion of gametes to form zygote. It is of two types., (a) Endogamy: it involves self fertilization I.e. both male and female gametes contributed by same parent(uniparental). E,g Taenia (hermaphrodite: monoecious)., (b) Exogamy: it involves cross fertilization I.e. fusion of two gametes formed by different parent (biparental) e,g man, dog, cat etc., 2. Conjugation: It involves temporary pairing of two parents which exchange their male pronuclei and then separate e,g paramecium., 3. Parthenogenesis: (virgin birth): It is the modification of sexual reproduction in which an egg develops into a complete offspring without fertilization.it is of two types :, a)natural parthenogenesis: it occurs naturally. It again of two types:, complete parthenogenesis: (thelytoky) in this type of parthenogenesis all the individuals develop parthenogenetically. All are females. No male is present in their life cycle. E,g Lacerta sexicola armaniaca., Incomplete parthenogenesis: (arrhenotoky)in this type of parthenogenesis either male or female develop pathenogenetically. It is monoparental e,g honey bee. In honey bee drone (haploid male) develops by parthenogenesis., Artificial parthenogenesis: in this type the egg is induced to develop into new individual artificially by changing Ph , prick of a needle, etc., Paedogenetic parthenogenesis: parthenogenesis in larval stage., Reproductive units, The reproduction units in sexual reproduction are specialized cells called gametes. The gametes are of two types; male gametes also called spermatozoa or sperms and female gametes also called ova or egg., Unisexual or dioecious: Animals in which male and female gametes are produced by male and female parents are called as unisexual or dioecious., Bisexual or monoecious or hermaphrodite: Animals in which both male and female gametes are produced by a single parent are called bisexual or monoecious or hermaphrodite e,g earthworm , Taenia etc., Mammalian reproductive system, Mammals are unisexual. The reproduction system of each sex consists of many organs. They are distinguished into primary, secondary and accessory organs., 1. Accessory (external) sex characters:, The external characters which distinguishes the two sexes I,e male and female are called as accessory sex characteristics. They include, Human reproductive system, The male reproductive system consists of :, Pair of testis, Scrotum, Vasa efferentia, A urethra, Certain glands, A pair of epididymis, A pair of ejaculatory duct, Penis, Scrotum: It is a pouch of pigmented skin arising from the lower abdominal wall and hanging between two scrotal sacs by a muscular partition, the septum scrota. The testis actually originates in the abdomen but later on the seventh month of development descends in the scrotal sacs through inguinal canal. the scrotum maintains testis at a temperature 2oc lower than that of the body, which is essential for the survival and activity of sperms. The scrotum is divided into two scrotal sacs by septum scroti. It is externally marked by a scar called as raphae. The testis are held in the scrotal sacs by spermatic cords and gubernaculum., Sometimes the testis fails to descend into scrotum, it is called as cryptorchidism., Surgical removal of testis is called castration or orchidectomy., 2. Testis: The testis are the primary sex organs . they are soft , smooth, pinkish organs about 4-5 cm long , 2.5cm wide and 2-3cm thick., (a) Protective coats: (Tunicae) The testis are lined by three protective coats: inner fibrous covering called tunicae albuginea ; middle vascular lining called tunica vasculosa and outer peritoneal covering called tunica vaginalis., (b) Testicular lobules: The testis are internally divided into some 250 lobules. Each testicular lobule consists 1-3 highly convoluted seminiferous tubules, blood vessels and nerves. The ends of seminiferous tubule converge and join to form straight tubules called tubuli recti. The tubuli recti open into rete testis., (c) Seminiferous tubules: Each seminiferous tubule is lined by germinal epithelial tissue. Majority of the cells are spermatogenic but a few are largely, pyramidal Sertoli or nurse cells. The spermatogenic cells produce haploid sperms by the process of spermatogenesis. The Sertoli/nurse cells provide nourishment to developing sperms., Sertoli/nurse cells: the nurse cells provides nourishment to the developing sperms. They also secrete androgen binding protein which concentrates testosterone in the seminiferous tubule and helps in sperm formation. They also secrete inhibin which decreases FSH secretion., (d) Interstitial cells (Leydig cells): Small groups of large , polygonal cells called interstitial or Leydig cells are present between seminiferous tubules. They secrete male sex hormone testosterone., 3. Vasa efferentia: 15 to 20 convoluted tubules called as vasa efferentia arise from rete testis and enter the head of epididymis., 4. Epididymis: The epididymis is a long tube which is divided into three regions: upper wider head or caput epididymis, middle narrow highly convoluted corpus epididymis and lower cauda epididymis. The sperms undergo maturation, increased motility and their fertilizing capacity increases in the epididymis. They pass to tail of epididymis for storage., 5. Vasa deferentia: it is a continuation of cauda epididymis about 40cm long. It passes over urinary bladder, curves round the ureter and join the duct of seminal vesicle to form ejaculatory duct. Near its end, the vasa deferens enlarge to form ampulla for temporary storage of spermatozoa., 6. Ejaculatory duct: they are about 2cm long , thin walled tubes, pass through the prostrate gland and open into the urethra., 1. Urethra: it is urinary duct leading from the bladder. It carries urine as well as sperms, secretions of Cowper’s and prostrate gland. It is long 20cm in males and passes through penis.it is divided into three parts :, - prostrate urethra: it passes through the prostrate gland. Sometimes prostatomegaly causes it constriction which leads to frequent micturition., - membranous urethra: it is the second part of the urethra., - penial urethra: it is that part of urethra that passes through the penis of male. The urethra opens to the exterior by opening called as urethral orifice/urethral meatus., 2. Penis: it is external copulatory organ. It is made of spongy tissue. The tissue has an abundant blood sinus that helps in the erection of penis. it possess two folds of corpora cavernosa and one column of corpus spongiosum. The corpus spongiosum forms penis glans at the tip. The tip of penis is highly sensitive glans . The penis is divided into three parts radix , corpus or body and penis glans . It also contains a number of sinuses which gets filled with blood that helps in the erection of the penis., 3. Accessory glands: it includes, a) Seminal vesicle; they are located near the ampulla of the vasa deferentia. They secrete yellowish fluid which contains fructose, hormone like prostaglandins, coagulating enzymes etc. fructose provides energy to sperm for swimming. Prostaglandins increases the muscular movements in the uterus the helps in sperm movement. Coagulating enzymes helps in coagulation of semen., b) Prostrate gland: it is large chest-nut shaped gland. It secretes milky slightly acidic fluid. It contains citrate (a sperm nutrients), fibrinogens, spermine,anticoagulant enzymes. The secretions nourish and activate the sperm to swim., c) Cowpers gland/bulbourethral gland : they secrete alkaline mucus. The mucus neutralizes any acid urine remaining in the urethra. It also makes the path lubricated for copulation., Semen, The sperm along with the secretions of accessory glands and mucus form semen. The semen has a pH of 7.35 to 7.50., Hormonal control, The growth , maintenance and function of male reproductive system are under the control of male sex hormone called testosterone. The FSH and ICSH regulates the secretions of testosterone etc. they are under the control of GnRH from hypothalamus., FSH = follicle stimulating hormone, GnRH = gonadotrophic releasing hormone., Puberty: It is the period when reproductive organs become functional. In males it is attained between the age of 13 – 16 years., Female reproductive system, The female reproductive system consists of :, A pair of ovaries, A pair of fallopian tubes(oviducts), Uterus, Vagina, External genitalis, Ovaries: The ovaries are primary sex organs of the female. They are about the size and shape of an almond. The ovaries are located in the lower part of abdomen. The ovaries connected to the broad ligament of uterus by mesovaria. They are also connected to wall of uterus by ovarian ligament and to the pelvic wall by suspensory ligament., Structure: The ovaries are composed of connective tissue, the stroma wrapped by a layer of cuboidal cells, the germinal epithelium. The stroma consists of outer ovarian cortex and central ovarian medulla. The ovarian medulla consists of many oval bodies called as Graffian follicles at various stages of development. Each follicle contains an ovum surrounded by follicle cells. The follicle cells secrete estrogen into blood. Once a month, the mature follicle from one ovary is released. The empty follicle after release of egg is called corpus luteum. The corpus luteum secrete progesterone during pregnancy. The degenerating corpus luteum is called corpus albicans., Fallopian tubes (oviducts): A fallopian tube is about 10-12 cm long muscular tube. It conveys the egg from ovary to the uterus. The fallopian tube shows four regions:, Infundibulum: it is broad funnel shaped proximal part. Its margin bears motile , finger like projections called fimbriae. It opens into the body cavity by an aperture called ostium. The fimbriae bear cilia which beat towards the ostium to direct the egg into the infundibulum., Ampulla: It is the long , wide part of the fallopian tube next to infundibulum., Isthmus: It is the very short, narrow and straight part that follows the ampulla., Uterine part: It is narrow part and communicates with the uterine cavity., Uterus: the uterus (womb) is large, elastic sac specialized for the development of the embryo. It is located between the urinary bladder and the rectum. It shows four regions:, a) Upper wide, dome shaped fundus that receives fallopian tubes., b) Cornua, the upper corners where the oviducts enter uterus., c) Middle large body or corpus ., d) Lower narrow cervix. The cervix communicates above with the body of the uterus by an aperture, the internal os and with the vagina below by an opening , the external os. The canal between internal and external os is called cervical canal., The wall of uterus is composed of three tissues: outer perimetrium , middle myometrium and inner endometrium., Functions: The uterus receives ovum, forms placenta and expels the young one at the time of birth., Vagina: It is a large, elastic, muscular tube about 7.5cm long. It is adapted for receiving male’s penis during copulation, allowing menstrual flow and as birth canal during partutition. Internally it possess vaginal rugae which becomes smooth after the first birth of child. The vagina opens in vestibule by vaginal orifice. This opening is lined by a tissue called as hymen in virgin females. The hymen breaks during the first sexual intercourse. It may also break by physical exercise etc., External genitalis (vulva): It consists of vestibule flanked by two pairs of fleshy folds of skin: labia majora and labia minora. A small erectile organ , the clitoris is also present which is homologues to human penis but is very small. It is lined by a fold of skin called as prepuce. Rubbing of clitoris during the process of copulation provides pleasurable sensation to the female. The posterior ends of labia minora are connected by fourchette. The part between the anus and the fourchette is called as perineum. A fleshy elevation above the labia majora is known as mons veneris or mons pubis. It bears pubic hair., A pair of vestibular or Bartholins gland occur one on each side of the orifice. They correspond to cowpers gland and secrete clear viscid fluid which lubricates path during copulation., Breasts: The breasts are rounded eminences located over pectoral muscles on the front wall of thorax. They enlarge in adult female. The breasts have a nipple and pigmented area called areola. They produce milk for nourishment of child., Gametogenesis, The process of formation of haploid gamete from diploid germ cells in the gonads for sexual reproduction is called gametogenesis., (haploid = 1n: diploid = 2n: gonads = testis and ovaries), Types, It is of two types:, Spermatogenesis, Oogenesis, Spermatogenesis: The process of formation of sperms (male gamete) in the seminiferous tubules of testis of male is called as spermatogenesis. It occurs in the seminiferous tubules of the testis. The seminiferous tubules contain germinal cells and few somatic cells called as sertoli or nurse cells. Spermatogenesis is divided into two phases;, a) This process of spermatogenesis has three phases: multiplication phase : growth phase and maturation phase:, a) Multiplication phase: The undifferentiated germ cells present in the seminiferous tubules of the testes are called as spermatogonia or sperm mother cells. The spermatogonia increases their population by repeated mitotic divisions such that newly formed cells are diploid (2n=46)., b) Maturation phase: On sexual maturity of the animal some spermatogonia stop dividing and grow in size by accumulating cytoplasm and replicating DNA, and then are termed the primary spermatocytes. The growth phase is called spermatocytogenesis., c) Maturation phase: The primary spermatocytes undergo first meiotic division and produce secondary spermatocytes. This division is reductional so that each secondary spermatocyte contain half or haploid (n=23) number of chromosomes. The secondary spermatocytes undergo second meiotic division and produce spermatids. This division is equational., 2. Formation of spermatozoa: The spermatids modify into spermatozoa or sperm. The transformation of spermatids into spermatozoa is known as spermateleosis or spermiogenesis. It involves movement of cell organelles to positions characteristics of mature spermatozoa etc. development of sperm takes 2-months. The fully formed sperm in the seminiferous tubules pass to vasa efferentia, then to epididymis for temporary storage. the sertoli cells provide protection and nourishment to developing spermatozoa., Spermatozoa: It consists of four parts I,e head , neck , middle piece and tail., Head : It is oval shaped and is composed of posterior nucleus and anterior acrosome. Acrosome is formed from Golgi body. It contain hydrolytic enzymes and help in penetration of egg during fertilization., Neck: The neck possess two centrioles: proximal and distal centriole. Proximal centriole helps in cleavage of zygote and distal give rise to axial filament., Middle piece: It contains mitochondria which provide energy for movement of sperm in the female genital tract. The mitochondria gets spirally arranged in the middle piece (nebenkern)., Tail: The tail helps in swimming in search of ova or egg. It also contains axial filaments developed from posterior centrioles., Release of sperm from the Sertoli cells into the lumen is called as spermiation., Oogenesis --, The process of formation of haploid ova (female gamete) or egg from diploid oogonia is called oogenesis. The process of oogenesis takes place in the ovaries of female. The egg formation begins before birth but is completed only after fertilization., Oogenesis consists of three phases: Multiplication , Growth and Maturation phase., a) Multiplication phase: in female foetal ovary undifferentiated germ cell present in the ovaries are called as oogonia or egg mother cells. They undergo mitotic divisions and form mass of cells called as egg tube which changes into egg nest. One cell in the egg nest grows and is surrounded by follicle cells. It become primary oocyte. Other cells in the nest become the follicular epithelium to protect and nourish it. The structure thus formed is called primary ovarian (Graffian follicle). The primary oocyte remains at prophase of meiosis-1., b) Growth phase: it is very long and extends over many years. Its cytoplasm increases and nucleus enlarges after puberty. In growth phase vitellogenesis occur in many eggs. The size of developing ova increases. In humans growth phase may take 13 years., c) Maturation phase: like spermatocyte, a fully grown primary oocyte also undergo first meiotic or maturation division and produces two daughter cells. One daughter cell is extremely small, where the other is almost as large as primary oocyte itself. It receives almost all cytoplasm and the small cell is known as first polar body or polocyte. The egg is released from the ovary in secondary phase. Both have haploid or (n) number of chromosomes. The large cell called as secondary oocyte undergo second meiotic division which does not proceed beyond until a sperm enters it. After fertilization , the second meiotic division is completed forming two cells one small and other large. The large one is called as the ootid and the small one is called as the second polar body., One primary oocyte forms after two meiotic divisions, one haploid egg and three haploid polar bodies. Development of an ovum takes about 13-years. The polar bodies have no function but they enable the egg to get rid of excess chromosome. In human, ova are released from the ovary in the secondary oocyte stage. Their maturation is complete in the reproductive tract of female., Ovulation: the release of egg from ovary is called ovulation. In the female ovulation takes place about 14-days before the start of next menstruation., Ovum: It is rounded , non-motile cell. It is almost free of yolk and is said to be alecithal. It has abundant cytoplasm called ooplasm having large nucleus termed germinal vesicle and surrounded by plasma membrane also called oolemma. Tiny vesicle called cortical granule lie just under the eggs plasma membrane. The side of egg which extrudes polar bodies is called animal pole and the opposite is called as vegetal pole. The ovum is enclosed by two additional egg coats: inner thin zona pellucida and outer thick corona radiata . zona pellucida is primary egg membrane and corona radiata is secondary egg membrane. In some eggs another covering called as shell may also be present. They are called as cleidoic eggs. It is secreted by fallopian tube and is called as tertiary membrane., Primary egg membrane: secreted by egg itself., Secondary membrane: secreted by follicular cells., Tertiary membrane: secreted by oviduct., Homolecithal egg: yolk uniformally distributed., Telolecithal egg: yolk towards one end., Centrolecithal egg: yolk in the centre and surrounded by cytoplasm., Menstrual cycle: the gamete formation in female is a cyclic activity that takes about 28-29 days and involves changes in the structure and function of the entire reproductive system. It is called menstrual cycle. It occurs only in primates (monkeys, apes, human beings). The first menstruation begins at puberty and is called as menarche. In human female the menstrual cycle terminates at 45 – 50 years of age and this stage is called as menopause., The menstrual cycle consists of 3 – phases:, 1. Follicular phase 2. Luteal phase 3. Menstrual phase., 1. Follicular phase: this phase lasts for 14 – days. It comprises the following events:, -The anterior pituitary lobe secretes follicle stimulating hormone(FSH)., -The FSH stimulates growth of ovarian follicle and maturation of oocyte., - It also stimulates secretion of estrogen from follicle cells. Estrogen inhibits secretion of FSH and stimulates secretion of luteinising hormone(LH)., - The LH stimulates ovulation. It occurs on 14th -day of menstrual cycle., - The estrogen also stimulates the uterus to prepare for implantation. It causes the development of myometrium and endometrium. The proliferation of endometrium continues., 2. Luteal phase or Secretory phase: this phase lasts for about 10 – days. It involves following events:, - the LH hormone causes development of corpus luteum from the follicle which has undergone ovulation., - the progesterone is secreted by the corpus luteum., - progesterone causes further development of endometrium., - LH maintains corpus luteum., - the progesterone also helps in implantation., - the estrogen and progesterone maintains endometrial lining. The wall of uterus also secreted a highly nutritive fluid called as uterine milk which is essential for sperms and ovum., - if fertilization occurs the corpus is maintained for nine months. The HCG hormone secreted by placenta also takes over function of LH and maintains placenta., 3. menstrual phase/bleeding phase, - it lasts for 3 – 5 days., - If fertilization does not occur, the secondary oocyte undergo autolysis and progesterone inhibits release of LH., - Reduction of LH , causes regression of corpus luteum and progesterone level falls down in blood., -the uterine lining dies due to deficiency of progesterone and is sloughed off. Blood vessels rupture causing bleeding. The lining of the fallopian tubes breaks down. The cast off uterine and fallopian tube tissue , blood etc pass out through vagina. This process is called menstruation or menstrual flow. It occurs after 25- days and lasts for 3– 5 days. It is also called “funeral of unfertilized egg’/ weeping of uterus for lost ovum., - Lower level of progesterone causes release of FSH which initiates new cycle., - If fertilization occurs, the zygote is implanted and placenta release HCG hormone. This maintains corpus luteum which releases progesterone and maintains pregnancy., - the first day of bleeding is regarded as the first day of menstrual cycle., Amenorrhea: disorder in which no menstrual cycle occurs., Hypermenorrhea: disorder in which excessive menstrual flow occurs., Dysmenorrhea: painful menstrual flow is called as dysmenorrhea., Estrus cycle: in case of non primate mammals another cycle called as estrus cycle occurs., Proestrus: the reproductive tract of female becomes ready for implantation., estrus phase: during this phase the ovulation occurs. The female becomes receptive to male. It is also called as heat period., Anestrus: no estrus cycle occurs during this period., Some mammals such as cow, buffalo shows oestrus cycle throughout year. Oestrus cycle of rat is of 5 – days., Monoestrus: single estrus cycle in a year., Biestrus: two estrus cycle in an year., Polyestrus: many estrus cycles during an year., Important points, Male sex act involves 3-phases: erection of penis, copulation and subsidence of erection., Nulliparous woman (who has not born any child)., Multiparous woman(who has born one or more child)., In unmarried / virgin female the vaginal orifice is covered by a membrane called as “hymen”., Main disorders of male reproductive system are: prostatomegaly (swelling of prostrate gland). Impotence (inability of penis to achieve erection). Sterility (inability of male sperm to fertilize egg)., Main disorders of female reproductive system: sterility (inability of female to conceive)., Breast cancer; Cervical cancer; ovarian cyst., Miscarriage: Inability of zygote to implant properly., Pregnancy test: HCG is detected in the urine., Circumcision : To cut off a part of prepuce as religious rite., Fertilization, Fusion of a haploid male gamete (spermatozoa) and a haploid female gamete(ovum) to form a diploid zygote is called fertilization., In human beings the fertilization takes place in ampulla of fallopian tube., Various events during fertilization, Arrival of spermatozoa: Male discharges semen high up in the female’s vagina during the process of copulation. This is called insemination. From here the sperm reach ampulla by their own effort and by the action of uterus. The sperm swims at the speed of 1.5 to 3 mm per minute. A single ejaculation of semen into the vagina contains 200 to 300 million sperms in 3ml of secretion. Only 100 sperms reach the fallopian tube., Arrival of egg: The egg is released from the ovary on the 14th day of the menstrual cycle. It is collected by the fimbriae of the infundibulum and directed towards ostium. Through ostium it enters into the fallopian tube. The non motile egg moves through the fallopian tube with the help of cilia and by the muscular movements of the oviducts., Capaciation of sperm: Capaciation is the process by which the sperm are made capable of fertilizing the egg by altering or removing certain molecules in the female genital tract. During capaciation influx of calcium occurs into the sperm. Also the cholesterol is removed from its surface., Chemical and physical events of fertilization: It consists of :, a) Acrosomal reaction: the ovum reaching the fallopian tube is surrounded by zona pellucid and corona radiate. The capaciated sperm pass through corona radiate to reach zona pellucida. Binding of the sperm head to the receptor molecule ZP3 helps in recognition and after recognition the acrosome reaction is induced . Acrosome releases its its hydrolytic enzymes by exocytosis like:, hyaluronidase that hydrolysis the hyaluronic acid which helds follicular cells together., corona penetrating enzyme dissolves corona radiate., acrosin helps in digesting zona pellucida., These three enzymes are collectively called as sperm lysins., All these enzymes dissolve egg membrane (zona pellucida and corona radiata) and enable the sperm to reach plasma membrane of the egg and fuse with egg plasma membrane. Binding of sperm to the egg induces depolarization of egg plasma membrane. Depolarization causes fast block to polyspermy., Cortical reaction:, In this reaction, the cortical granules present beneath the egg’s plasma membrane fuse with the plasma membrane and release their enzymes between the plasma membrane and zona pellucida. These enzymes harden the zona pellucid which now acts as the sure block to polyspermy., Karyogamy: The entry of sperm into the egg induces the egg to undergo meiosis –ll. After this the nucleus of the sperm seperates from middle piece and tail and become male pronucleus. The nucleus of ovum become female pronucleus after meiosis-ll. The chromosomes of sperm are set free by the break down of nuclear envelope. Mixing up of the chromosomes of spermatozoa and ovum is called karyogamy or amphimis. This complete the act of fertilization. The ovum is now a diploid cell having 23 – pairs of chromosomes and is termed “zygote”. The mother is said to be pregnant., Cleavage, It refers to a series of rapid divisions of the zygote following fertilization forming a many celled blastula., Cleavage in human zygote occurs during its passage through the fallopian tubes to the uterus. It is holoblastic, I,e it divides the zygote and the blastomeres completely into daughter cells. The blastomeres differ in size from the start., The first cleavage takes place about 30 – hours after fertilization. It is meridonial, coinciding with the animal – vegetal pole axis. It produces two blastomeres one slightly larger the than the other. The second cleavage occurs within 60 – hours after fertilization. It divides each blastomere into two by forming a mitotic spindle in each. The larger blastomere divides a little sooner than the smaller one so that there is a transitory 3 – cell stage before the 4 – cell stage. Third cleavage takes place about 72 – hours after fertilization., Cleavage produces a solid ball of small blastomeres. The embryo now looks like a mulberry and is known as morula. cleavage is radial and indeterminate in the human zygote. Radial cleavage means at 8 – cell stage the upper 4 – cells are directly above 4 – cells. In indeterminate cleavage , each blastomere formed by early cleavage division retains the capacity to develop into a Complete embryo., Morula : It consists of 8 - 16 cells but is not larger than zygote. It consists of two types of cells, outer larger of small cells around an inner mass of larger cells. The morula reaches the uterus about 4 – 6 days after fertilization. It is surrounded by zona pellucida that prevents its sticking to the uterine wall., Blastocyst or blastula, The outer cells of the morula now absorb the nutritive fluid secreted by uterine mucous membrane and is called as trophoblast or trophectoderm. The fluid absorbed collects in a cavity called blastocoels. As the quantity of fluid increases the morula enlarges rapidly and is called blastocyst. Inner cell mass looks like a knob and is called embryonal knob., The side of blastocyst to which embryonal knob is attached is known as animal pole. The trophoblast does not take part in formation of embryo but forms extra– embryonic membrane like chorion and amnion., As the blastocyst is formed, zona pellucida becomes thinner and finally disappears., Implantation, The attachment of blastocyst to the wall of uterus is called implantation. It takes seven days after fertilization. The contact of implantation stimulates rapid division of trophoblast cells which destroys endometrial cells by releasing lytic enzymes. The blastocyst sinks into the pit formed in the endometrium. The embedded blastocyst forms villi all around to obtain nourishment., HCG (Human Chrionic Gonadotrophin): The trophoblast cells develop the chorion (an extra-embryonic membrane), which later forms placenta. The chorionic cells secrete a hormone HCG. The HCG maintains corpus luteum and stimulates it to secrete progesterone. The progesterone maintains endometrium lining throughout pregnancy and hence prevents menstruation., By 16th week of pregnancy, the placenta itself produces enough progesterone and corpus luteum regresses. Progesterone causes increased secretion of mucus in the cervix that forms a protective plug during pregnancy., HCG is used to check pregnancy., Gastrulation, The process in which blastocyst is transformed / changed into gastrula with three primary germ layers by rearrangement of cells is called gastrulation., Process: The cellular movement during gastrulation is called as morphogenetic movement. The three germ layers formed are; ectoderm , mesoderm , endoderm., 1) Formation of endoderm: Some cells covering free surface of embryonal knob differentiate and become flat, form the first endodermal cells. Then they rapidly multiply spread out in all directions forming a complete lining. This lining constitutes the endoderm. The endoderm tube so formed is the primitive gut or archenteron. Its cavity called gastrocoel is earlier blastocoels with a changed lining., 2) Formation of mesoderm: At the caudal margin (hind end) of embryonic disc, the cells start proliferating at an increased rate. The proliferated cells later detach from the embryonic disc and spread between the trophoblast and the endoderm. The new layer of cells so formed is the mesoderm., 3) Formation of ectoderm: After the formation of mesoderm, the remaining cells of the embryonic disc get arranged in a layer called ectoderm., Organogenesis: The process of formation of organs from the three germ layers is called organogenesis., 1) Ectoderm : It give rise to:, Epidermis of skin, Epidermal derivatives like glands, nails, hair., Nervous system, Eye (conjunctiva, cornea, lens, retina etc), Internal ear, Salivary gland, Enamel of teeth etc., 2) Mesoderm: It gives rise to:, Dermis of skin, Most muscles, Connective tissue, Kidneys, Gonads, Heart, Blood vessels and lymph, Spleen, Most of the skeleton, Dentine of the teeth, Notochord., 3) Endoderm: It forms;, Lining of gut, Gastric and Intestinal glands, Liver, Pancrease, Thyroid , Parathyroid and Thymus gland, Lining of trachea, bronchi and lungs, Lining of middle ear etc., Embryonic or Foetal membranes: The embryonic or foetal membranes protect the embryo within the womb of mother. Four foetal membranes are formed: yolk sac; amnion; chorion; and allantosis., Yolk sac: It is formed below the embryo. It contains fluid, not yolk. Its wall first consists of trophoblast and endoderm. At this stage, it is called primary yolk sac. Later, the wall of yolk sac comes to consist of endoderm and mesoderm. At this stage, it is called primary yolk sac. Later, the wall of yolk sac comes to consist of endoderm and mesoderm. It is now called secondary yolk sac. The yolk sac functions as the site of blood cell formation until 6th week, when the liver takes its role. Thereafter it shrinks., Amnion: it is formed above the embryo. It consists of trophoblast inside and mesoderm outside. It encloses a fluid – filled space, the amniotic cavity., The amniotic fluid is derived from foetal kidney and bladder i.e; it is foetal urine. It is completely replaced every 24-hours. its functions are;, It cushions embryo and protects it from bumps and pressure of maternal organs., Permits foetal movement., Maintains a constant temperature and pressure etc., Allantosis: It is a small sac that pushes out from the gut of the embryo near the yolk sac by the third week. It forms umbilical arteries and veins which grows upto the chorion to vascularise it. It also forms blood cells. It consists of endoderm enside and mesoderm outside., Chorion: It is completely surrounds the embryo. It is composed of outside and mesoderm inside. It protects embryo and forms placenta., Placenta, It is defined as the temporary intimate connection between foetal and maternal tissue for nutrition, respiration etc of the foetus., Structure: A fully formed human placenta is a reddish brown disc less than 1 kg in weight. Its foetal surface is smooth and has umbilical cord attached near its centre. It consists of chorion only. Hence called as chorionic placenta or haemo-chorial placenta. The placenta has two parts: the part contributed by the foetus i.e., chorionic villi or foetal placenta and the part shared by the mother I, e part of uterine wall called maternal placenta., Different types of placenta:, Yolk sac placenta: It is formed in kangaroo., Chorioallantoic placenta: It develops in most eutherian mammals., Chorionic placenta: It occurs in humans., There are five types of placenta regarding the number of tissue layers which separate the foetal blood from the maternal blood. In the basic type, 6 layers separate the foetal and maternal blood. Foetal endothelium , connective tissue and trophoblast and uterine epithelium, connective tissue and endothelium. The exchange of material between the maternals and foetal blood occurs through these 6 layers. Other types of placenta arise from basic type by erosion of certain tissues. This makes the exchange more efficient., Epitheliochorial placenta: All six tissue layers of the placenta remain intact e,g horse., Syndesmochorial placenta: Uterine epithelium is eroded e,g cow., Endotheliochorial placenta: Uterine epithelium and connective tissue are eroded e,g dog., Haemochorial placenta: All the 3 uterine tissues are eroded so that foetal villi are bathed directly in maternal blood flowing in lacunae e,g humans., Haemoendothelial placenta: All the 3 uterine tissues and 2 foetal tissues viz trophoblast and connective tissue are eroded. Thus foetal capillaries lie in the blood lacunae of the uterus. E,g rabbit., Functions of placenta:, 1. Nutritive organ: Food material passes from the mothers blood into the foetal blood through placenta., 2. Digestive organ: The trophoblast of placenta digests proteins before passing them into foetal blood., 3. Respiratory organ: Gas exchange of co₂ and o₂ also occurs through placenta., 4. Excretory organ: Nitrogenous wastes, like urea pass from foetal blood to maternal blood through placenta., 5.Endocrine organ: Placenta secretes human chorionic gonadotrophin , estrogen, progesterone and human placental lactogen., 6. Barrier: the placenta does not allow a large number of substances to cross placenta. However some harmful substances may pass placenta and can damage foetus. They are called as teratogens like thalidomide., Parturition, Meaning : It is the expulsion of full – term young one from the mothers uterus at the end of gestation., Process: Gestation (pregnancy) is completed in about 280-days from the start of mothers last menstruation. There are certain hormones released by the baby which after crossing placenta stimulates pituitary gland to secrete oxytocin. Oxytocin stimulates uterine contractions. This provides force to expel the baby from the uterus causing birth., Oxytocin also stimulates release of prostaglandins from the placenta which stimulates more contractions of uterus., Labour: The forceful muscular contractions of uterine wall leading to parturition are called labour. On the completion of gestation, labour starts. It causes labour pain:, First stage (dilation): It lasts for 12- hours. Regular peristaltic contractions of uterine wall move the foetus down towards the cervix which expand fully. Amnion and chorion ruptures. The amniotic fluid passes out which lubricates vagina. Foetal placenta is pulled out which makes young one free, Second stage (expulsion): it lasts for 20 – minutes to one hour. With the help of uterine contractions, the young one is gradually pushed outward through the dilated cervix and vagina and is finally delivered (born) into the outside world, where it draws its first breath. The umbilical cord is ligatured at two place and cut between ligatures. This frees the baby totally., 3. Third (placental) stage: It lasts for 10 – 45 minutes after the infants birth. Minutes after the deliver, the uterus begins to shrink. This frees the placenta. Now the placenta, umbilical cord and fetal membranes are expelled by another series of uterine contractions. These structures are referred as the “after – birth”., In about 28 – 35 days, the uterus returns fully to its non pregnant state by decrease in size and restoration of endometrium., Lactation, Production of milk in the female’s breasts following the birth of a young one in mammals is called lactation. During pregnancy , the breasts enlarge due to growth of mammary glands. Secretion and storage of milk begins after birth of the young one under the influence of prolactin. The actual release of milk called milk letdown , requires presence of oxytocin., Secretion of prolactin and oxytocin depends on suckling produced by the nursing infants on the nipple of the breasts., Composition of milk: Milk contains proteins (casein , lacta-albumin ), fat , sugar (lactose), vitamins , water etc. A nursing mother secretes 1 – 2 litres of milk daily., Colostrum: After birth , the breasts first release not milk but colostrum for 2 – 3 days. It is thin , yellowish fluid often called fore – milk. It is nutrient rich and transfers antibodies from mother to the baby., Twins, Sometimes one human female produces 2 – babies at a time. This is called twinning . one of the two young produced at the same time is termed twin. Twinning is of two types:, From one egg: if early blastomeres separate before their fate is fixed, each can develop into a complete young one. They are always of same sex, have identical traits. They are called identical twins / monozygotic., From two eggs: sometimes , two eggs one from each ovary , may be released simultaneously. Both are fertilized by a separate sperm. Each zygote develops into a young one. They may be of same or different sex and different traits. They are called non identical or fraternal twins or di-zygotic twins., Important points, Cesarean section: sometimes the foetus fails to come out and a surgical procedure , called cesarean section is needed. The baby is removed through a cut given in the mothers abdomen., Miscarriage / abortion: if the embryo is abnormal , or dies , secretion of hcG stops, and this lowers the progesterone output by the corpus luteum. This in turn causes breakdown of the endometrium and a consequent miscarriage or abortion, that is loss of embryo. It usually occurs during ist month of pregnancy., Mammalian egg lacks centriole. This is contributed by the sperm which helps in process of cleavage., Cone of reception(fertilization cone): a conical outgrowth given by the egg of frog to receive the sperm. Not found in human egg., Sex of a baby is determined by the father not by mother., Hyaluronidase , corona penetrating enzyme and acrosome are called sperm lysins and are released from acrosome during acrosomal reactions after the sperm entry., Menarche: first menstrual flow in the life of a girl., Artificial insemination: technique of fertilizing the female ovum by artificially introducing semen into vagina., Reproductive health, Reproductive health addresses the reproductive processes, functions and systems at all stages of life of an individual. Reproductive health means that people are able to have a responsible, satisfying and safe sex life and they are able to reproduce. The concept of reproductive health was introduced at the international conference on population and development at cario in the year 1994. It was later on accepted by WHO., According to WHO reproductive health is defined as total well being in all aspects of reproduction,`its emotional, behavioural and social aspects along with the physical one., A society will be reproductively healthy if its members possess not only physically and functionally normal reproductive organs but also have normal emotions and behavioral interactions among them in all sex related aspects., Significance: Or aim of reproductive health programme is to provide a responsible , safe and satisfying reproductive life., To create awareness: With the help of audio visual aids , print media , health centers , government and non government agencies , teachers are engaged in creating a general awareness in both males and females about various aspects of reproductive and related issues., To provide sex education: Sex related education has been included in school curriculum with an aim to provide proper sex education to the young and adolescents in order to remove myths and misconception related with various sex aspects. It helps to maintain a proper sex hygiene, to know early about harms of sex and sexually transmitted diseases., To educate the fertile couples: The reproductive group must be educated about birth control measures , prenatal and post- natal care of mothers and child , importance of breast feeding., Sexually Transmitted Diseases, STDs or Veneral diseases (VDS) or reproductive tract infections (RTI) are those infections or communicable diseases which are transmitted from an infected person to a healthy person through sexual contact or sexual intimacy., STDs have increased many folds due to changing pattern of sexual behavior and increasing resistance in the pathogen to antibiotics. So STDs are easier to avoid than to treat and cure., Prevention of STDs: All STDs e,g Gonorrhea , Syphilis , Genital herpes , Genital warts, Trichomoniasis, Chlamydiasis, hepatitis B, AIDS etc are transmitted via sexual contact. Although hepatitis B and AIDS can also be transmitted through sharing of those articles which are contaminated with blood like surgical instruments, injections , transfusion of blood and from infected mother to foetus., All STDs are often called silent infections because they remain unnoticed and undetected in early stages due to lack of symptoms. When symptoms appear it is often too late. Further due to social stigma the infected person avoid to consult a doctor for medical treatment in view of shyness and conservative approach of society. Prevention is better than cure for STDs. Following preventive measures can control STDs:, Avoid sex with multiple partners ., Be faithful to your partner., Always use condoms If felt that partner is suffering from any reproductive tract infections . I, e ABC formula. Here A = absistence (avoid sex with multiple partners) , B = be faithful, C = maintain character and use condoms., Earlier detection of an STD is essential for its proper cure and treatment. Always consult a qualified doctor for proper diagnosis and treatment. Do not feel shy or unease while diagnosis or check up. Treat it like other diseases., Chlamydiosis: It is the most common bacterial disease caused by pathogen Chlamydia trachomatis . it is characterized by following symptoms like thick pus like discharge from penis and painful urination in males. It causes inflammation of cervix , uterus and uterine tubes in females and if remained untreated than may transform into pelvic inflammatory diseases (PID) causing sterility., Prevention: Avoid unsafe sex and multiple sex partners, Therapy: Antibiotics like tetracycline , erythromycin are effective drugs., Gonorrhea: It is caused by diplcoccus gram negative bacteria called as Neisseria Gonorrhea. Incubation period is about 2 – 10 days., Symptoms: As the bacterium passes into genital tubes it causes inflammation of mucus membrane of urinogenital tract so that the patient feels burning sessation during urination. Symptoms are more visible in males than females. It may cause arthritis and eye infection., Therapy: Pencillin and ampicillin are most effective drugs., Syphillis: It is caused by spirochaetae bacterium Treponema palladium. In males the infection leads to pain less ulcers on the penis after the incubation of about 9 – days. The ulcers look red and become dry and hard sore called chancre appears in the genitalia. Similar symptoms appear develop on labia minora and labia majora and also on vagina. If this diseases is not treated at this stage than tertiary signs appear in heart , liver and brain. If syphilis reaches the brain it can cause paralysis and loss of memory., Treatment: pencillin and tetracycline are most effective drugs., STD caused by viruses, Genital warts: The disease is caused by a virus Human papilloma virus (Hpv). It spreads through sexual intercourse with infected partners who may be even symptom less., Symptoms: it is characterized by the appearance of warts on the genital organs like penis , labia , around anus , in vagina and on the cervix. These warts vary in appearance from tiny bumps to large masses., Therapy: they can be removed with the drug condylox, freezing with nitrogen laser surgery or treatment with alpha interferon., Genital herpes: the diseases is caused by Herpes simplex virus. It spreads through sexual contact with the person having multiple sores., Symptoms: the visible primary symptoms are periodically recurring watery blisters on the genitalia or buttocks , fever ,painfull urination and swollen lymph nodes in the groin. Infection spreads by rupturing of blisters and release of virus. The drug Acyclovir inhibits the appearance of new sores and shortens the time for sore to shed the viruses., Hepatitis B: see for detail in unit – iii., Population Explosion and Birth Control:, During the last century the science and technology has progressed a lot. This progress has improved the quality of life, provided better health facilities and checked various fatal diseases. All these conditions lead to an enormous increase in population , which is commonly called as population explosion., The world population as estimated in 1900 was around 2 – billion (2000 million). It reached 6 – billion by 2000. A similar trend was observed in india. Our population was approximately 350 – million at the time of our independence I, e 1947. It has crossed 1 – billion mark on may 11th 2000. It means that every sixth person in the world is an Indian. India is second most populous country in the world after china. It is projected that our population will reach 1.53 billion by the year 2050 surpassing china. A rapid decline in death rate from 44.1 / 1000 in 1901 to 8.7 / 1000 in 2001, as well as increase in number or people in reproductive age., A slow decline in birth rate from 45.8 / 1000 in 1901 to 26.1 /1000 in 2001, are the probable reasons for the increase in population. According to the 2001 census report the population growth rate is still around 1.7% I, e (17 / 1000) at this rate our population could double in 33 years. This alarming growth rate could lead to an absolute shortage of resources even the basic requirements I,e food , shelter and up serious measures to check this population growth rate., Birth control – Need and Methods, There is an immediate need to control the population , so that the benefits of development may reach to every citizen and every one will enjoy the improved standard of living. This is only possible through fertility control or birth control. Birth control means regulation of family size through deliberate control of conception , that means children by choice and not by chance. It is carried out by family planning or family welfare measures., Family planning is a programme which is based on certain objective like avoiding unwanted births , conceive as and when desired , spacing the birth of children and determine the number of children recognized as a basic human right., According to WHO , the modern concept of family planning includes – proper spacing and number of counselling for sterility. Screening of cervical and breast cancers, pregnancy test and provision of adoptive services., Uncontrolled population: The ill and harmful effects of population explosion must be known to every body. So that one should not only feel responsible but also act responsible., Eradication of social evils: Sex abuse and sex related social evils mostly occur in such a society which is ignorant in sex education. Therefore spreading message of reproductive health is need of hour., Infra – structure: Strong infrastructure facilities , professionals , experts and material support are needed to attain proper reproductive health by providing assistance in reproductive health related problems like pregnancy , menstrual problem , infertility and STDs., Sex determination: There is now a blanket ban on determination of foetal sex through amniocentesis and other techniques and female foetal genocide. The census of india 2011 shows decrease in sex ratio and invites our immediate attention towards this moral degradation., Contraception: Contraception means the temporary or permanent measures or methods that prevents unwanted pregnancies or contraception . for making contraception motivation are the print media and electronic media. A common slogan posters is “ hum doo hamaray doo” in order to accept the small family norm. most educated persons, especially the working class have adopted this norm. rather some have gone further down by adopting one child norm. officially raising marriageable age 18 years for girls and 21 years for boys and providing incentives to parents with small family. gifts may be given at the birth of a female child. These measures will help in resolving the problem of over population., Methods of contraception or birth control measures: The contraceptive methods may be grouped into two classes:, 1. The spacing or temporary methods and 2. Terminal or permanent methods., Spacing or temporary methods: these methods are commonly used to postpone or provide a gap or space in between the birth . these methods are chosen by those couples who are not interested to have children at this stage or wants to maintain a gap after the birth of first child., Barrier methods: they are mechanical devices which prevents the deposition of sperms into vagina and their passage into uterus. They can be inserted by the user himself at the time of copulation. The common barrier methods are:, Physical or mechanical methods: the mechanical methods includes the use of the condoms. condoms are tubular rubber or latex sheaths rolled over penis before sex. These are most widely used by males and popularly known as nirodh which in Sanskrit means prevention. As they prevent deposition of semen in vagina and also provide protection from STDs., Diaphragms: it is a tubular rubber sheath with a flexible metal or spring ring at the margin which is fitted inside the vagina, ., Chemical method : They are chemical contraceptives which contain various spermicidal agents in the form of creams e, g (Delfen), jelly (perceptin), pastes , foam tablets (aerosol , lactic acid , boric acid , citric acid, potassium permanganate and zinc sulphate)., Intrauterine devices (IUDS): Intrauterine contraceptive devices (IUDS) are those devices which are made of plastic metal or a combination of the two which is inserted into the uterus to prevent contraception. IUDs are called loops, spirals , rings, bows , shields. Depending upon the shape IUDS are of three types: inert – copper releasing and hormone releasing. The inert IUDS are made of polythene impregnated with barium sulphate or stainless steel e, g lipple loop. The exact mechanism of inert IUDS contraception is not clear., Copper IUDS commonly called copper –Ts have ionized copper which slowly diffuses at the rate of some 50 mg /day . the copper ions may affect sperm motility capacitation and survival of sperms. The inactive sperms are unable to fertilize the ovum. These devices needs to be replaced after 3 – 5 years , when the copper release become less or insufficient , e,g Cu T 200, multiload CuT 250 , multiload CuT380 etc., Hormone releasing IUDs: progesterone IUDs e, g progestasert and levonorgestrel IUD. These devices release small quantities of hormone which increases the viscosity of the cervical mucous and there by prevent sperm from entering the cervix. The high level of progesterone and relative low level of estrogen makes it unfavorable for implantation., Natural methods of contraception: these are those methods which do not require any device, medicine or religious sanction. They are of three kinds : safe periods . withdrawal method and breast feeding., Periodic absistence: ovulation occurs midway of menstrual cycle I,e on 14th day. The egg remains alive for 48 – hours. Avoiding sex during this fertility period will naturally prevent contraception . the fertile period is considered between the 13th and 18th day of menstrual cycle., Withdrawal method: withdrawal of penis before ejaculation during coitus will prevent deposition of semen into female reproductive tract and prevent conception. it is old method. But it is not safe always because some of the sperms may be present along with the secretions of cowpers and other glandular secretion., Lactational amenorrhoea (absence of menstruation): sometimes no ovulation or menstruation occurs during lactation period after parturition. It is safe period and no conception occurs during this period but it is effective only upto few months., Oral contraceptive oral pills, They are preparations which contains progestin = progesterone alone or a combination of progesterone and estrogen. These are the hormonal contraceptives taken orally in the form of birth control pills. The progesterone and estrogen combinations inhabit secretions of FSH and LH from anterior lobe of pituitary gland so these inhabit ovulation from ovary and implantation. They also retard the entry of sperms in the uterus .commonly used hormonal pills are mala – D daily and saheli (weekly)., Terminal or permanent methods of contraception: Surgical contraceptives are permanent methods of family planning . in this method the reproductive function of an individual male or female is permanently destroyed. These surgical methods are also known as sterilization. The surgery done in male is called vasectomy and on females is tubectomy., Male sterilization, Vasectomy: It is a surgical method of sterilization. Vasa deferens of both the sides is cut and the cut ends are ligated so that sperms are unable to pass down in the male reproductive system. The surgery is simple and can be performed under local anesthesia., ., Female sterilization, Tubectomy : It is the surgical procedure of female sterilization where a portion of both the following tubes is cut and then ligated to block the passing of ovum through them., Tubal ligation involves the blocking of fallopian tubes by an instrument called laparoscope., Medical Termination of Pregnancy (MTP), Abortion is defined as the termination of pregnancy before the fetus becomes capable of living. Abortion may be spontaneous (natural) or induced or voluntary. The intentional termination of pregnancy before the fetus is fully formed is termed as medical termination of pregnancy or induced abortion. Nearly 45 to 50 million induced abortions are performed every throughout the world. It accounts 1/6th of the total conceived pregnancies in a year. MTPs performed a significant role in decreasing population although they are not performed for that purpose. Whether to accept or legalize MTPs or not is a question of debate in many countries due to emotional , ethical , religious and social issues involved in it., In 1971 government of India passed the medical termination of pregnancy act in parliament for the first . this act is a health care measure which helps to reduce illegal female foeticides. According to this act woman can abort , the fetus under following conditions:, When the contribution of pregnancy is harmful or can endanger the health of mother., When the fetus is suffering from several physical or mental disorders., This act authorize only a registered , medical practioner to perform abortion in a hospital run or registered by government., MTPs are considered relatively safe during the first trimester I.e. 12 weeks. Second trimester abortions are more riskier. Another dangerous trend is that majority of MTPs are performed illegally by unskilled and unqualified persons which proves fatal and results death of mother. The most shameful act is the miss use of amniocentesis if the foetus is found to be female. It is terminated by MTP, which is totally against ethical , religion and legal practices . effective counselling is need for mothers who need no conception to adopt contraceptive methods rather to go through MTP., Infertility, Infertility (in = not; fertilis = fruitful): infertility is the inability to conceive or produce children even after two years of regular of unprotected sex. It is of two types: primary infertility means patients who have never conceived. Secondary infertility is found in those patients who have previously conceived., Infertility is caused by defects found in males, females or in both. In India still female is blamed for infertility which is not the reality in all cases., Causes of infertility: A woman may be infertile due to following causes:, 1. Anovulation: It is the failure of ovary to ovulate and is considered the most common cause of infertility in females. The cause of this infertility is that pituitary or hypothalamus fails to produce the FSH which is essential for follicle development and maturation of egg or LH which is needed for the release of egg from the ovary., 2. The fallopian tubes may be blocked or narrowed in some woman. So the movement of egg is adversely affected hence fertilization is impossible. This defect can be treated by laser surgery., 3. Damage to uterus: In about 5 – 10 % cases infertility is caused due to damaged uterus. The uterus is unable to support pregnancy I, e fertilized zygote does not get implanted., 4. Damage to cervix: the cervix is the neck of the uterus. The cervix may become damaged because of abortion or difficult birth. It interferes with the movement of sperms., Male infertility, Azoospermia : absence of sperm in the semen is known as azoospermia. This may occur because of the lack of sperm production or due to blockage of tubes (vasa deferens ) so that the sperm do not appear In semen. This blockage can occur due to an infection or an injury. Failure of ejaculation is another reason., Oligospermia: low sperm count is called oligospermia(normal count over 200million)., Abnormal sperms: abnormal sperms may possess two heads or no tail or may have abnormal shapes., Impotence: the inability of male to achieve an erection of the penis is known as impotence., Premature ejaculation: it means release of semen before the penetration of penis into the vagina., Assisted reproductive technologies (ART), During the last one decade medical technology has progressed a lot by achieving mile stone developments in various fields. One such development is the diagnosis and correction treatment of some of the disorders which enabled the child less couples to have children., Specialized health care units have been established where such infertile couples are assisted to have children by certain special techniques. All these special techniques are called assisted reproductive technologies which include the following techniques ; 1. Test tube baby 2. GIFT 3. IVF 4. ZIFT., Test tube baby: (IVF-ET): invitro fertilization is the technique of fertilization carried out in a glass container outside the body of the mother. In this method which is popularly known a test tube baby ova from the wife or donor female and sperm from the husband or donor male are collected and are induced to form zygote under stimulated conditions in the laboratory. Then the zygote or early embryos upto 8 – blastomeres could then be transferred into the fallopian tube ZIFT., ZIFT: zygote intra – fallopian transfer is the technique in which zygote upto 8 – blastomeres is transferred into uterus ., IVF: the technique in which ova are injected outside the ovary of desired female and the sperms are collected from the husband and their fertilization is carried out in laboratory in a test tube I.e. artificially is called as invitro fertilization., GIFT: (gamete intra fallopian transfer) this method is used females who cannot produce ova but can provide suitable environment fertilization and further development of embryos in the oviduct. In such cases , ovum from the donor female is surgically removed and is then introduced into the fallopian tube of such females. Such woman accept sperms from her husband during copulation., All the above techniques require extremely high precision handling by specialized professional and good facility., Amniocentesis, Trans-abdominal aspiration of fluid from the amniotic sac of the fetus is called amniocentesis., Use: It is a prenatal diagnostic technique to determine the genetic disorder, if any, sex of the fetus., Procedure: The fetus bathes in the amniotic fluid that fills the amniotic cavity. At an early stage of pregnancy 14th or 15th week , the location of the foetus and placenta is determined by sonography. Then a small amount of amniotic fluid is drawn by passing a special surgical needle through the abdominal wall and uterine wall into the amniotic sac containing amniotic fluid. Cells that have sloughed from the fetus skin or respiratory tract into fluid are sucked into the syringe. These cells can be examined for chromosomal abnormalities such as Dows syndrome, Klinefelter’s syndrome etc. resulting from non disjunction of chromosomes . the cells can be be cultured and in about a fortnight enough cells become available for test. The cells and fluid are also tested for the metabolic disorders such as phenylketonuria etc. if it is clear that the child is likely to suffer from an incurable congenital defect , the parents will have a clinical justification for abortion., Misuse of amniocentesis: Unfortunately, the useful technique of amniocentesis is being misused to kill the normal female fetuses so determination of sex by this way has been banned., Chorionic villi sampling: Amniocentesis is possible without a chance of injuring the foetus with the needle only after the sixteenth week of pregnancy. At this time , abortion is not safe. A new technique named chorionic villus sampling(cvs) can be done during the eight to tenth week of pregnancy when abortion is safe for the woman. For cvs , the doctor inserts a narrow flexible tube (catheter) into the uterus through the mothers vagina and cervix guided by ultrasound and sucks small amount of fetal tissue (chorionic villi) from the placenta. The cells of chorionic villi are then used for karyotyping. Cvs provides a mass of rapidly dividing foetal cells, thus facilitating the examination of genetic disorder., Advantages of cvs: It has some advantages over amniocentesis:, It is done in lesser time., It can be performed early I, e between the 8th and 10th week of pregnancy., Unit – II, Sex Determination, In diploid organisms the sex is determined by a specific pair of chromosomes called as sex chromosomes or heterosomes. All other chromosomes are called as allosomes, which control somatic traits., Chromosomal sex determination is based on heterogametic I, e formation of two kinds of gametes in one sex. The main genetic mechanism of sex determination are:, XX – XY type: this type of sex determination takes place in case of mammals like human beings , certain insects etc. in human beings the female has similar sex chromosomes I,e XX and male has dissimilar sex chromosomes I, e XY. The y- chromosome is shorter than X. though dissimilar , X and Y chromosomes synapse in meiosis, segregate and pass into different gametes., During gametogenesis , two types of sperms are formed. One sperm with X – chromosome and another with Y – chromosome. All the eggs formed are alike each with X – chromosome. Thus female is said to be homogametic and male is said to be heterogametic and it produces two types of gametes. This condition Is called male digamety. Sperms with y – chromosome are called as androsperms and with X – chromosome are called as gymnosperms., The sex is determined at the time of fertilization., The egg with x – chromosome fertilized by a sperm with y – chromosome will become a zygote with xx – chromosome., The egg with x – chromosome fertilized by a sperm with y – chromosome will develop into a male., It A represents an autosome, the genetics of sex in human beings can be given as;, XX – X0 : it operates in certain insects like cockroaches , grasshoppers bugs. The female has two homomorphic sex chromosomes (xx) and is homogametic. It produces similar eggs with x – chromosome. The male has one sex chromosome only and is heterogametic. It produces two types of sperms: gymnosperms with (x) and androsperms without (x). fertilization of an egg with (x) – chromosome bearing sperm yields female offspring and by no –x sperm yields male offspring. The ratio of offspring is 1 : 1., ZZ – ZW: it occurs in certain insects ( butterflies and moths ) and in vertebrates like fishes , reptiles and birds. The male has two homomorphic sex chromosomes (zz) and is homogametic and is heterogametic. There are thus two types of eggs I, e with z and with w and only one type of sperms I, e each with z., Fertilization of an egg with z – chromosome bearing sperm will develop into a male., Fertilization of an egg with w – chromosome bearing sperm will develop into a female., The offspring has sex ratio of 1: 1., ZO – ZZ: it occurs in certain insects ( butterflies and moths ) and in vertebrates like fishes , reptiles and birds. The female is heteromorphic which produces two types of eggs: half with (z) and half without (z) chromosome. The male is homomorphic and homogametic., It forms only one kind of sperms. On fertilization by a sperm with z – chromosome, the z – containing egg gives rise to a male offspring (zz) and z – lacking egg produces a female offspring (zo)., ., Haploid – diploid mechanism of sex determination: Hymenoptera insects, like bees, wasps, ants etc. shows a unique phenomenon in which an unfertilized egg develops into a male and a fertilized egg develops into a female . therefore, the male is haploid (1n) and the female is diploid (2n). eggs are formed by meiosis but the sperms are formed by mitosis. Thus sex is determined by the number of chromosomes., Male honey bee Female honey bee, 16-chromosomes(1n) 32 – chromosomes (2n), Mitosis meiosis, Sperm Egg, Fertilization, Female honey bee, Haploid – diploid mechanism of sex determination in honey bee, Environmental sex determination:, In some animals , there is environmental determination of sex like:, In Bonellia , a marine worm , the swimming larva has no sex. If it settles down alone, it develops into a large (2.5cm) female. If it lands on or near an existing female , a chemical from her causes the larva to develop into a tiny (1.33) male. Male lives as a parasite in the uterus of the female., In turtles , a temperature below 28 oc produces more males , above 33 oc produces more females and between 28 oc -33 oc produces males and females in equal proportion., In bacteria , fertility gene a factor located in plasmid determines the sex. It is also called “non – allosomic genic determination of sex”., Mendelian disorders, These genetic disorders are mainly caused by alternation and mutation in the single gene. They are transmitted to the offspring following principle of inheritance. Some of them are as under:, Hemophilia: (bleeders diseases) It is a sex linked disorder produced due to gene mutation of sex chromosome-x. types: hemophilia – A due to deficiency of factor viii (anti-hemophilic factor AHF)., Hemophilia – B caused due to deficiency of factor ix (Christmas factor)., Complication: Continuous bleeding of even minor wounds, joint damage, transfusion infection, intracranial hemorrhages, adverse reaction to clotting factor replacement therapy., Life expectancy: Before treatment availability 11-years and now after availability of treatment 50 – 60 years., Inheritance pattern: Hemophilia is a sex linked (x-linked) disorder. Affected males are hemizygous for the trait as they possess only one allele for the trait on their sex chromosome x. females mostly act as carrier as they possess two allele for the trait on their two x – chromosomes. Of one allele is mutated another normal allele compensates for the mutated allele and no adverse effects are manifested. Hemophilic females do not survive. From above crosses it is quite evident that males pass the trait to their sons from whom it will be again transferred to them. Hence it is also known as skip generation inheritance of crisscross inheritance or zig – zag inheritance or sex linked inheritance., Red – green color blindness: It is also known as Daltonism as John Dalton (himself a sufferer) published a paper on it in 1798 . Wilson 1911 located the gene for red – green color blindness on x – chromosome. it is a sex linked (x – linked) disorder. We possess two types of photoreceptors cells in our retina, rods and cones. Cone cells are of three types viz: erythrolabs (sensitive to red light), chlorolabs (sensitive to green light) and cyanolabs (sensitive to blue light ). Red – green color blindness is caused dur to mutation of the gene in chlorolabs responsible for formation of green pigment sensitive to green light. Due to this a person cannot distinguish red color from green color hence the name., Inheritance pattern: same as in hemophilia as both are sex linked disorders:, Males are never carriers., Colorblindness is common in males than females., Colour blind females always have colour blind father and always produce colorblind sons., 3.Sickle cell anaemia: It is an autosomal disorder found widely in tropical Africa and also in American blacks. It is characterized by sickle shaped (crescentic) red blood corpuscles formed under low oxygen conditions. Change in shape of RBCs is due to the presence in them a defective type of haemoglobin called sickle cell haemoglobin designated as Hbs , due to mutation of HbE gene on short arm of chromosome – ii. The disease is manifested in homozygous recessive condition only. Heterozygous individuals acts as a carrier. The gene involved in sickle cell anaemia codes for β – polypeptide chain of haemoglobin – the o2 carrying protein in RBCs. Sickle cell anaemia develops in the individuals due to change In just one nucleotide pair in its DNA. I, e thymine is replaced by adenine. This alternation results in the substitution of one amino acid valine for glutamic acid which is the sixth amino acid in the β – popypeptide chain of Hb. This small change turns haemoglobin A into haemoglobin S. the diseases is manifested only in homozygous recessive state I, e (Hbs, Hbs). About half of affected individuals die by the age of 20., Effect of SCA: It has a pleiotropic effect. When the red blood cells containing haemoglobin faces o2 shortage , their molecules aggregrate and form stiff fibres. These fibres distort the cells into odd shapes such as sickles. Due to inflexibility , the sickle shaped corpuscles cannot easily squeeze through narrow capillaries. The sickled cells get stuck in the small capillaries and reduce circulation to the regions supplied by these vessels. The cells also breakdown decreasing RBC number that leads to anaemia. It also leads to tiredness , headache , fever , muscle cramps , poor growth , jaundice , failure of kidneys and heart etc., Advantages of SCA : 20 to 40 % African have sickle cell allele in heterozygous condition. It lowers the chance of developing malaria. The parasite of malaria in sickle cell die. The remaining parasite are destroyed by the body defense before malaria develops. Thus the sickle allele in heterozygous condition protects the person against malaria., Normal HbA gene Sickle cell HbS gene, -CTC - - CAC –, -GAG- -GTG-, mRNA – GAG- mRNA – GUG-, prevention: birth of children with fatal SCA can be avoided by discouraging marriages among heterozygous (carriers)., SCA can be treated with hydro urea drug , which produces fetal hemoglobin , which doesn’t sickle., History of SCA:, Queen Victoria of England (1819-1901) was a carrier and her son Leopod had this defect. Since none of her ancestors and relations were hemophilic, the mutation probably occurred in sex cells of her father a mother or in one of her own germ cells. Leopod survived to father a daughter who was also a carrier. Haemophilia spread to royal families of Spain and Russia through the marriage of two of victories daughters., Alkaptonuria: it is an inborn metabolic disorder produced by the action of single gene., Symptoms:, Blackening of urine on exposure to air., Darkening of certain cartilage., Urine of alkaptonuria person contains homogensitic acid, also called alkapton which combines with o2 to form a black pigment. This pigment slowly deposits in the cartilage of ears and nose. It also causes mild arthritis., Cause: In normal person, a liver enzyme homogensitate oxidase catalyse the breakdown of homogentisic acid to compounds that enter krebs cycle to produce co2 and H2o. the alkaptonuria are unable to breakdown homogentisic acid because of absence or inactivity of the enzyme needed for this purpose. Lack of enzyme is due to absence of the normal form of the gene that synthesis the enzyme. Hence homogentisic acid accumulates and is excreted in urine., Phenylketonuria (PKU): It is an inborn metabolic disorder. It is caused due to accumulation of phenylalanine in blood, cerebrospinal fluid and urine. In human body amino acid phenyl alanine is converted into another amino acid tyrosine by phenylalanine hydroxylase (PAH) enzyme., phenylalanine tyrosine, Due to mutation of PAH on chromosome 12, this enzyme is not formed or is inactive . as a result large amount of phenylalanine accumulates in the body fluids and tissues and effects organ like central nervous systems and cause mental retardation. the retention of phenylalanine also effects metabolism of tyrosine melanin. This explains why persons with phenylketonuria generally have blonde hair(pale yellow) ; blue eyes and a fair skin. Phenylalanine are excreted in urine hence the name phenylketonuria., It can be controlled by taking diet in which phenylalanine free. Meat , chicken , eggs, cheese , cow milk should be avoided as they are rich in phenylalanine., Albinism : It is also a recessive inherited disorder., Symptoms:, Lack of dark pigment (melanin) in the skin, hair , iris., Disorder of eyes due to damaging effect of bright light., Cause: It is caused due to absence of enzyme tyrosinase which is necessary for synthesis of the pigment melanin from dihydroxyphenyl – alanine. The gene for albinism (a) does not produce the enzyme (tyrosinase) but its normal allele (A) does. Thus only homozygous recessive individuals (aa) is affected., Dihydroxyphenyl alanine tyrosine, Melanin, Muscular dystrophy, This disorder causes deterioration of muscles at an early age. The mutated gene on X-chromosome fails to produce a protein called “dystrophin”. This protein is thought to relay the nerve’s signal to Ca2+storage sacs in the muscle cell. As a result ca2+ is not released. Further ca – level trigger the release of an enzyme that destroys actin and myosin. The victim becomes invalid by the age of 10 and dies by the age of 20., Downs syndrome: (Mongolian) trisomy of 21 – chromosome. It was first reported by Langdon Down in 1866., Symptoms: It is characterized by round face, broad forehead., A Mongolian type of eyelid fold, nasal bridge., Permanently open mouth, projecting lips , protruding tongue., Short neck, flat hands and stubby fingers., The victim has little intelligence due to malfunction of the brain., Genitalia and gonads are under – developed., Cause: it is an aneuploid, trisomy disease., It is caused by the presence of an extra chromosome no. 21. Both the chromosomes of the pair 21- pass in the mothers’ ovary. Thus the egg has 24- chromosomes instead of 23, and the offspring has 47 – chromosomes (45 + XY in males and 45 + xx in females), instead of 46 chromosomes. The presence of three chromosomes of the same kind is called trisomy. It is also called 21 – trisomy., Aged woman above 40 – years have greater chances of producing offspring with Downs syndrome., Familial Downs syndrome may run in the family. It arise by translocation of a large segment or whole of the chromosome – 21 to another chromosome remains normal (46) but there is an extra chromosome 21., 2) Klinefelter’s Syndrome: Trisomy of sex chromosome. It is an aneuploid condition with 3 – sex chromosomes., Symptoms: the person with this syndrome is a sterile male with small testis, usually long legs, obesity and sparse body hair and with many female characters such as breasts(gynecomastia).The victim usually has normal intelligence., Cause: it is caused by XXY – genotype. This genotype results from the union of a non – disjunct XX – egg with a normal Y – sperm. The individual has 47 – chromosomes (2n + 1). It occurs once in 2000 live births., 3) Turners syndrome: It is an aneuploid condition with a single sex chromosome(monosomy)., Symptoms: the individual with this syndrome is a sterile female with underdeveloped breasts, reduced ovaries, small uterus , loose skin of neck, mostly normal intelligence and short stature and with many male characteristics such as heavy neck muscles and narrow hips. She may not menstruate or ovulate. Its incidence is 1 in 5000 births., Cause: Turners syndrome is caused by XO – genotype. It results from the union of an abnormal O- egg with a normal X-sperm , or a normal X- egg and abnormal O – sperm. The individual has 45 – chromosomes (2n – 1). It is only viable monosomy in humans., 4) Edward’s syndrome: Trisomy of 18 – chromosome (2n+1)., 5) Patau – syndrome: Trisomy of 13 – chromosome(2n + 1)., 6) Cri – du – cat syndrome: Due to deletion of one of 5th chromosome . the effected child during early children life produces sound resembling mewing of a cat. Hence named so., 7) Super female: Genotype XXX, XXXX, XXXXX with total chromosome no. 47, 48, 49. Such females show abnormal sexual development and mental retardation., 8) Super males: they have genotype XXY. They have unusual height, mental retardation, and criminal bent of mind. They are more aggressive than normal males and usually overproduce male hormone(testosterone)., Origin of life, Life is the inherent capacity of organisms to utilize the outside materials (light, water, gases or food) for energy, growth and reproduction through chemical reactions ( metabolism) in a controlled manner., Various theories of origin of life are as under:, Theory of special creation: it is a religious theory. It stated that life was created by some supernatural power , the creator or God. According to Christian belief God created the universe , mostly plants , animals and human beings in six natural days. Adam and Eve were first man and woman created by God. According to Hindu mythology Brahma created Manu and Shraddha first. This theory is purely religious concept , acceptable only on the basis of faith. It is not a scientific fact., Theory of spontaneous generation ( abiogenesis):, It stated that life originated from non – living material in a spontaneous manner:, It was believed that a hair from tail of white horse when dropped into water will develop from rotten meat., Flying insects were believed to develop from mud of river Nile., A dirty shirt when placed in a dark room with some grains in it develops rats/ mice after few weeks., This theory was challenged by spllanzi; Redi, and finally laid to rest by Pasteur., 1) Redi’s experiment: Redi placed meat or fish in three jars. One jar was left open, one covered with gauze and one was covered with paper. The meat / fish decayed in all jars and attracted flies. The flies entered open jar and laid eggs which then hatched into larva. No flies developed in other two jars. This showed that animals arise from the eggs and not from non- living matter., 2) Pasteur’s experiment: He showed that even minute organisms such as protists and bacteria arise from the pre – existing organisms such as protists and bacteria. He took hay infusion in a flask and bent its neck into s – shaped curve. He then boiled the infusion for several minutes. This killed the micro – organisms and made the infusion sterilized. On cooling the escaping steam condensed into water in the lower part of s – tube. It stopped entry of micro – organisms into flask. No life appeared for months. But in the water trap in s – tube many types of micro – organisms developed. Thus it also proved life exists from pre – existing life.(biogenesis), 3) Theory of catastrophism: It stated that there have been several creations , each preceded by a catastrophe due to some geological disturbances. Each catastrophe completely destroyed the life and each creation consisted of life quite different from that of previous one., 4) Interplanetary theory: It stated that life had reached the earth from some other heavenly body in the form of resistant spores of simple organisms in meteorites of in spaceships. Finding fertile soil here, they grew and then evolved into the existing forms. The theory is also called spore theory or theory of panspermia., Modern or Oparin – Haldane theory: it is also called chemical theory, naturalistic theory or primary abiogenesis., This theory explained how and when life appeared. The theory was proposed by A. I Oparin and J.B.S Haldane. The various steps involved are as under:, a)chemical evolution b) biogenesis, Evolution of chemicals is thought to have four major events:, (1) Formation of inorganic molecules: The high temperature (100 0C)of early earth rpeve3nted atoms to form molecules as the heat disrupts bond. As earth cooled molecules like H2,NH3,CH4,CO2,and water vapors were formed with help of energy in the form of sunlight, lightening or volcanic eruptions., (2) Spontaneous formation of simple organic molecules:, The inorganic molecules formed later on interacted with each other & formed simple organic molecules like sugars , fatty acids , Glycerol ,Amino acids ,organic bases(purines ,pyrimidines ) Etc.{Miller’s Experiment proved it.}, (3) Spontaneous formation of complex organic compounds (Polymers):, The small , simple organic molecules came together and combined to form large complex biological molecules e.g., Simple Sugars Starch Amino acids polypeptides, Nucleotides Nucleic acids., Haldane suggested that accumulation of organic molecules in sea formed dilute broth(soup)., Many scientists now hold that organic molecules formed a sludge instead of soup., (proved by the experiment of S. W. fox), Formation of molecular aggregate: Oparin and Sydney fox held that large organic molecules synthesized abiotically on primitive earth later came together spontaneously and due to intermolecular attraction formed large colloidal aggregrates called coacervates. The colloidal aggregates selectively absorbed proteins and other material from the ocean. On increasing in size , the coacervates divided into small ones., B) biogenesis :, a) Formation of eobionts: the coacervates had all the basic properties of living cells , such as growth , reproduction but lacked enzymes etc and control of nucleic acids. Later the nucleic took control of coacervates and showed process of duplication / replication. With this , the coacervates turned into first primitive living systems called Eobionts about 3 – million years back., b) Formation of first cell: some proteins by chance achieved the ability to catalyze chemical reactions that is act as enzymes. The speeded up synthesis of molecules and biochemical reactions., The lipid – protein bio membranes covered the eobionts growth and development was also regulated. These were the first cells probably., The first living organisms developed in reducing atmosphere (without o2). They were heterotrophs (anaerobes)., Then some cells developed process of chemosynthesis or photosynthesis for nourishment. Thus atmosphere arise., As o2 – accumulated in the atmosphere, the UV – light changed some o2 into ozone. The ozone formed a layer in the atmosphere., ( 2o2 + o2 203 ), First organisms formed were prokaryotic which with the passage of time developed eukaryotic cells with closed nucleus, cell organelles etc., From unicellular organisms gradually multicellular organisms were formed., Summary, Free atoms …………. H ; C ; N, Inorganic ………… H2 ; H2O ; CH4 ; NH3 ; CO2., Molecules, Simple organic ………….. CH4 ; H2O sugars , fatty acids, glycerol., Molecules NH3 ,amino acid, purines and Pyrimidines., Complex organic …………… sugars (monosaccharides) polysaccharides fatty acids + glycerol fat, amino acids, proteins nucleotides , nucleic acids DNA and RNA., Coacervates or microspheres - aggregates of large organic molecules, Eobionts - nucleic acid controlled coacervates, First primitive cells - lipid – protein membrane bound enzyme and nucleic acids regulated., Main steps in origin of life by Oparin and Haldane, Fox’s experiment: S. W. fox has synthesized polypeptides by heating a mixture of amino acids to 130 to 180 0c for several hours and then cooling them in water. He called these molecules protenoid microspheres (1 – 2µm) in diameter., Millers experiment: showed synthesis of simple organic molecules from simple inorganic molecules like co2, H2o, CH4, etc. Miller and Urey designated a glass apparatus comprising of a glass flask, condenser and a liquid flask. The apparatus stimulated the conditions on the primitive earth. He circulated in this apparatus mixture of CH4, NH3, H2 in 2: 2: 1 ratio and H2o – vapour at 800oc. He provided energy in form of electric spark of 75000 volts from electrode in the gas flask. He kept the experiment working for 18 – days. A mixture of small organic molecules was formed in the gas flask. On analysis he found amino acid, glycine , alanine and aspartic acid etc., Evolution, The term evolution literally means to unroll or unfold. Change in element with time is inorganic evolution and change in living organisms with time is called organic evolution or biological evolution., “ The present day complex organisms have originated during the course of time from the earlier simplier forms of life by a process of abrupt change in accordance with the environmental requirements (charles Robert Darwin)., According to Theodosius Dobzhansky “nothing in biology makes sense except in the light of evolution.”, Evidences of organic evolution, The various evidences of organic evolution are categorized as morphological, embryological, paleontological , biogeographical , physiological etc., 1) Body organization: All organisms are made up of cells. Cells aggregate together to form tissues. Tissues gather to form organs and organs cooperate to form organ system. This organization is the fundamental unity of all animals., 2) Homologous organs: The organs of different species which have similar basic structures and origin but perform different functions are called as homologues organs. The term was proposed by Richard Owen and is based on divergent evolution., Example: forelimbs of vertebrates like man, cheetah, whale, bat etc. they have different shape of those organs and show different functions. They are used for grasping in man, running in cheetah, swimming in whale and for flying in bat. They however have same built plan. In each case forelimb consists of upper arm having single bone humerus; forearm containing two bones in wrist , metacarpals in the palm and phalanges in the five digits. They inherited it from an ancestor which had five – digited or pentadactyl limbs. They got modified during the course of evolution., Insects mouth parts are also homologous organs., 3) Analogous organs: the organs of different species have different basic structures and origin but perform same functions are called as analogous organs. Analogy is based on “convergent evolution., Example: Insects and bird wings: both these organs are used for flying in air but they are different in structure., An insect wing is an extension of the integument, where as a bird wing is formed of limb bones covered with flesh, skin and feathers. the superficial similarity of these organs is due to adaptation to flying rather than to inheritance from a common ancestor. Similarity fins and flippers of dolphins are also analogues organs., Flippers pentadactyl; fins not pentadactyl, Connecting links, The organisms which possess characters of two different groups of organisms are known as known as the connecting links. E, g euglena, peripatus , lung fishes , egg laying mammals etc., Euglena: It is a connecting link between plants and animals. Its plant characters are paired fins, dermal scales and gills. Amphibian characters are internal nares , single or double lungs , 3 – chambered heart. It suggests evolution of amphibian from fishes., Lung fishes: It is a connecting link between fishes and amphibians. Fish character are paired fins, dermal scales and gills. Amphibian character are internal nares , single or double lungs , 3 – chambered heart. It suggests evolution of amphibian from fishes., Egg laying mammals; Connecting link between reptiles and mammals. Mammalian characters are hair, mammary glands etc. reptilian character are shelled eggs, cloaca etc. it shows evolution of mammals from reptiles., Neoplina: Annelida and Mollusca., Peripatus: annelid and Arthropoda., Vestigial organs, The organs which occur in reduced form and are useless to the possessor, but are homologous to the fully developed organs of related animals are called as vestigial organs. These organs were fully developed functional and necessary in the ancestor and disappearing due to change in their mode of life. Example: in humans there are about 90 – vestigial organs., 1) Tail bone: it is small bone at the end of sacrum. It consists of 4 – fused vertebrae. It is a vestige of the tail of ancestral form., 2) vermiform appendix and caecum; vermiform appendix is a blind tube at the end of the caecum in certain mammals including man. In herbivorous like rabbit, horse etc. caecum and vermiform appendix serve for digestion of cellulose content of the food by bacterial action. In man the habit of taking soft and cooked food has reduced the need for bacterial digestion. The caecum and appendix persist in man , because they were present in the ancestral forms., The other vestigial organs are:, 3) canine and wisdom teeth, 4) third eye lid (nictitating membrane), 5) auricular muscles of pinna., Atavism, Atavism is the reappearance of a certain ancestral structure which has either completely disappeared or greatly reduced., Example: the occurrence of short tail in some babies , presence of additional mamma in two rows down the front of the body of some persons, power of moving pinna in certain cases, large canine etc., The presence of these structures only In a few individuals of a species can be explained in the assumption that there is a tendency among the animals to develop structures of their remote ancestors., Embryological evidences, The comparative study of the embryology of different animal groups shows striking structural similarities between them. All animals start life as a single cell, the zygote. In all cases, the later changes into gastrula having in most cases three primary germ layers, namely ectoderm, mesoderm and endoderm. The entire animal develops from these three layers., The early embryos of all vertebrates resemble in shape and structure. They have similar head with eye and ear rudiments etc. this indicates evolutionary relationship of the adult vertebrates., Recapitulation theory, Given by von Baer in 1828 and was later called biogenetic law by Ernst Haeckel. It states that “ontogeny repeats phylogeny”. Ontogeny is the life history of an individual animal. Phylogeny is the evolutionary history of the race of the animal. This means an organism repeats its ancestral history during its development., Example: frog has its development an aquatic, fish like tadpole larva. The latter has a tail fin for swimming and gills for breathing in water. This stage indicates that the frog has evolved from a fish like ancestor., Paleontological evidences, Paleontology is the study of past life based on fossil recorded. The fossils are the remains or impression of the ancient organisms preserved by natural means in some medium. The medium in which the fossil occur include sedimentary rocks, amber, ice, ash of volcanoes , sand ,mud etc. fossils provide sufficient information regarding evolution., Kinds of fossils, Fossil kind Mode of formation Example, a)Entire organism frozen in ice wholly mammoth, or found in Siberia, unaltered organism, b)skeletal material trapped in sedimentary bones, teeth, shells, rocks. Chitin exoskeleton, c)moulds and casts hard parts trapped in gastropods and, sediments that harden to rock port land ., dissolve leaving its impressions, as a mould. This may be filled with, material and harden to form cast., d)petrified remains tissues replaced by water carried petrified forests, mineral deposits of, . Arizona., e)impressions remains in fine grained sediments archaeopteryx, on which organism died. Feathers , leaf, impressions ., f)imprints footprints , tracks etc made dinosaur footprint., in mud., g)coprolites faecal pellets buried in coenozoic sediments. Mammals, Missing links, The fossil organisms which show characters of two different groups of animals are called the missing links., Example: fossils of Archaeopteryx lithographica (180 million years ). It shows characters of birds and reptiles., Avian character: it possessed feathers, jaws modified into beak, forelimbs modified into wings etc., Reptilian character: it possessed teeth in the jaws, claws on free fingers, a tail with caudal vertebrate etc., Huxley so described birds as “glorified reptiles”., Adaptative radiation or divergent evolution, It is the process of evolution of different species in a given geographical area in which different members of same ancestral species are evolved along different lines in different habitats of same area. It is an example of divergent evolution., Example: 1. Adaptative radiation in marsupials:, Darwin explained that the marsupials (meta therians) in the presence of less number of eutherians , survived, flourished and evolved along different lines by divergent evolution in Australia regions., 2.Homologous organs as explained earlier., Physiological or biochemical evidences, Comparatively biochemistry also shows relationship among the animals. The aspects of biochemistry that indicate biochemical affinity are metabolic processes viz digestion, respiration;, Enzymes ; hormones; blood and lymph; blood proteins; blood groups ;molecular homology etc., Theories of organic evolution, The modern theories which explain mode of evolution (origin of species ) are as under:, Lamarck’s theory of the inheritance of acquired characters., Darwin’s theory of natural selection., De Vries mutation theory., Modern concept of evolution., Lamarck’s theory of inheritance of acquired characters:, This theory of organic theory evolution was forwarded by French biologist chevalier de Lamarck. He explained it in his famous book ‘philosphie zoologique’ in 1809. This theory is based on three factors:, New needs: environment means aggregate of external conditions , things etc which affect existence and development of an organism. Variation in environment requires efforts to fulfill its needs and adapt in environment. These efforts leads to a change in habits and behavior of an organism. The new habits involve extensive use of certain organs and disuse of others., Acquisition of characters : Characters are acquired by the organism to meet new needs in three ways: innate tendency; use and disuse of organs ; effects of an environment ., Innate tendency: Evolution occurs by an innate tendency so as to adapt perfectly to environment. Thus Lamarck believed that evolution responded to organism needs., Use and disuse of organs: Continuous extensive uses of the organs to cope with environment keeps them active and make them larger, stronger and more efficient. Continued disuse gradually makes them weaker and smaller so that they tend to finally disappear., Effect of environment: Variation in environment factors such as temperature, light, food, wind, enemies etc effect living organism and produce change in their bodies. The change brought about by use and disuse of organs and by influence of environment factors in an individual during its life time are called as ‘acquired characters’., Inheritance of acquired characters: The characters acquired by an individual through use and disuse of organs and through environmental factors as explained above are transmitted by heredity to next generation. Thus evolution is a slow or gradual process. Thus the existing species are the sum total of characters acquired by their predecessors in many generations., Example: (Giraffe) the giraffe is a mammal with very long neck and forelimbs. It has evolved from a deer like ancestor with small neck and forelimb. Their ancestor’s lived in barren places where leaves of the trees were the only food available to it. In making an effort to reach the leaves , it continuously stretched its neck and forelimbs. This resulted its slight elongation of these parts. The increase acquired in one generation was transmitted to the next generation in which further elongation occurred. After a number of generation present day giraffe with a long neck and long forelimbs were produced., Criticism: The tendency to increase in size has been noted in many forms, but many times evolution shows reduction in size. E,g angiosperms , shrubs and herbs are more advanced and have evolved from trees. Moreover persons continuously busy in reading and writing using their eyes more than others, develops impaired sight. Why their eyes do not become more efficient., 2) A hard blow to Lamarckism came from German biologist August Weismann who proposed “ theory of continuity of germplasm”. This theory proposed that environment affect only somatic cells and not germ cells. Characters are transmitted by germ cells and not somatic cells. Hence acquired character must die with the death of organism., 3) Weismann cut off tails of rats for about eighty generations and allowed them to breed, but tailless were never born. Similarly boring of pinna , circumcision etc are not transmitted from one generation to another. Hence Lamarckism was rejected., Mutation theory, This theory was put forth by Dutch botanist Hugo De Vries (1901) in his book “species and varieties “their origin by mutation. According to this theory new species arise by the appearance of sudden changes in the pre – existing ones. Darwin called such changes as sports and de Vries called them as mutation., De Vries mutation theory was based on the observation on evening primrose (Oenothera lamarkiana), which grow wild in his garden. The main postulates of the mutation theory are as under:, New species evolve by sudden , distinct, discontinuous and heritable changes called as mutation., All organisms have an inherent tendency to mutate and individual with mutation are called mutants., Mutations are indeterminate. They may be useful or harmful., Mutations may occur in different members of the same species, giving rise to several related new species., Mutations appear again and again , thereby by increasing the chance of natural selection., Criticism, Oenothera lamarkiana is an abnormal plant. It has chromosomal aberrations that effect the number of chromosomes and are unstable. The original 2N number is 14 but plants with 20, 24, 22, 28, 30 diploid number are not uncommon., Most of the mutations are recessive and deletions. Evolution is however, based on useful and dominant traits., Mutations are incapable of introducing new genes and alleles into a gene pool. Hence only mutations may not result in formation of new species., Mutation theory failed to explain symbiosis and mimicry., Darwinism, Charles Darwin an English naturalist (1809 – 1882) made an extensive study of nature for twenty years especially in 1831 – 1836 when he went on a voyage on the famous ship “ HMS Beagle” and collected a large number of animals, plants and fossils. He made observation an animal distribution and relationship between living and extinct animals. In 1838, Darwin was highly influenced by Malthus essay 1798 , on population. Coincidentally Alfred Russel Wallace after reading Malthus essay proposed his theory (on the tendency of varieties to deposit indefinitely from their origin type ) and send it to Darwin for consideration. In 1858, Darwin and and observations , so it retained his name . Darwin explained his theory in 1859 in his book, ” on the origin of species by natural selection”., Main postulates of Darwins theory, Rapid multiplication: all animals and plants tend to multiply in geometric progression. In other words , a population doubles its number in a first year, can increase to four times In a second year and eight times in a third year and so on. Every species produces more offspring than can be supported in a particular environment., Example: paramecium divides three times in 48 – hours. With this rate, single paramecium will produce in five years a mass of paramecium equal to ten thousand times the size of earth., Limited food and space: living organisms require food and space for existence. Space always remains constant and food supply does not increases at the same rate as that of population. So, it induces struggle for existence among living organisms., Struggle for existence: excessive multiplication and limited food and space leads to severe competition among the offspring for their requirements. This competition for primary necessities like food , space etc is called struggle for primary necessities like food, space etc is called struggle for existence., It is of three types:, Intraspecific struggle: Competition between the members of same species e,g two dogs of same species fighting etc. this type struggle is very severe as the needs of the organism of same species are similar., Interspecific struggle: Between members of different species e,g between a predator and a prey. A snake (predator) feeds upon a frog (prey). On the other hand frog (predator here) feeds upon insects (prey). Thus they form different food chains and enhance competition., Environmental struggle: It is the fight between living organisms and environment factors like heat, cold, flood, earthquake etc., Variation: It is the law of nature. Each individual varies in some respect such as size, shape, structure and behavior from others of its species. Even the offspring of same parents are never exactly alike except identical twins., Natural selection: (survival of the fittest) the process of sorting out the active and fit individual with useful variations by nature was called natural selection by Darwin and “survival of the fittest” by Herbert spencer. This means that stronger and well adapted individual survive and weaker and poorly adapted are eliminated or in other words nature selects the best of the lot., Inheritance of the useful variation: The individuals, after their selection by nature in the struggle for existence, pass on their useful variation to the next generation., Formation of new species: The inheritance of useful variation go on accumulating and after a number of generations the variations become so prominent that the individual turn into a new species. So Darwin says evolution is a gradual process and speciation occurs by gradual changes in the existing species or in Darwins words “ evolution is descent with modification., Criticism, Darwin could not explain the source of variation, nor could he attach any importance to mutation. Darwin proposed that only useful organs are selected in the struggle for existence. The vestigial organs serve no function. Yet they are being preserved generation after generation. Some organs in certain animals developed beyond the stage of usefulness e, g antlers of deer, tusks of elephants etc. these organs instead of providing benefit to their possessor, often hindrance in their life. There is no room for their selection in Darwin’s theory., Darwin explained survival of the fittest but not arrival of the fittest., Modern concept of evolution, Neo – Darwinism is modified version of the theory of natural selection and is a sort of reconciliation between Darwin's and De Vries (mutation) theory. The scientists who contributes to the out come of Neo – Darwinism believes that all sorts of changes passes through chromosomes or genes from one generation or other. Any change in genetic order can bring a variation or mutation., Main postulates of neo – Darwinism:, a) Genetic variability: The studies show that the units of heredity and variation are genes, which are located in a linear manner on the chromosomes. The sum of all the genes of all members of a population collectively forms the gene pool of that population. Various sources of genetic variability in a gene pool are :, Chromosomal aberrations: These include morphological changes in the chromosome without affecting no. of chromosomes. It includes deletion, duplication, inversion of genes etc., Numerical changes of chromosome: These include changes in the number of chromosomes. These may be euploidy, aneuploidy., Gene mutation: these are invisible changes in chemical nature of DNA of a gene and of is of three types:, Deletion: involves loss of one or more nucleotide pairs., Addition: involves gain of one or more nucleotide pairs., Substitution: involves replacement of one or more nucleotide pairs by other base pairs., Recombination of genes: thousands of new combinations of genes are produced by crossing over, chance arrangement of bivalents during gametogenesis and chance fusion of gametes during fertilization., Physical mutagens : radiations , temperature etc. and chemical mutagens like nitrous acid , colchicine’s etc., Genetic drift: it is elimination of the genes of some original characteristics of a species by extreme reduction in a population due to migration or epidemics etc., Natural selection: Natural selection off Neo – Darwinism differs from that of Darwinism in that it does not operate through survival of fittest, but operates through differential reproduction comparative reproductive success. Differential reproduction is the production of more offspring due to high reproductive rate of those organisms, which are best adapted to the environment , than those which are less adapted. If the differential reproduction continues for a number of generations then the genes of those individuals which produce more offspring , will become predominant in the gene pool of the population. Therefore natural selection cause progressive changes in gene frequencies., Reproductive isolation: Any factor, which reduces the changes of interbreeding between the related groups of living organisms is called an isolating mechanism. Reproductive isolation is must to allow the accumulation of variation leading to speciation by preventing hybridization. thus reproductive isolation helps in evolutionary divergence. Following are the methods of reproductive isolation., Morphological isolation; caused due to difference in the morphology of genitalia., Geographical isolation: caused due to physical barriers like mountains, hills, oceans, seas etc., Ecological isolation: caused due to difference in the habitat of related organisms., Behavioral isolation: due to difference in the courtship pattern., Genetic isolation: due to difference of the gene products., Physiological isolation: due to difference in the physiological processes., Thus according to Neo – Darwinism four basic steps of organic evolution are:, Appearance of genetic variability in certain members of the population., Spread of genetic variability over the population by differential reproduction., Some sort of reproductive isolation between the elementary species and the parental species., Accumulation of genetic variability leading to speciation., Speciation: A species is defined as a group of individuals having some basic similar characters distinct from other groups of individuals, interbreeding freely under natural conditions to produce fertile offspring's and sharing a common gene pool. Mostly the biologists believe that the process of mutation, genetic recombination, genetic drift, isolation and natural selection the forces that bring about origin of new species and evolution of the entire biological world., Evolutionary history of man, Paleontological evidences of evolution of man: paleontology deals with the study of fossil records of ancient animals. It provides very strong evidences in favor of evolution of man. Nevertheless the fossil records for human evolution are not continuous. However fossils collected from various regions do indicate certain trends in human evolution and also give some idea about the possible origin of the human. So the evolutionary history of man can be traced as under:, Dryopithecus: In early Miocene there existed a group of apes, ape like animals collectively called as Dryopithecus. Africans formerly known as proconsuls exhibits close similarity to the chimpanzee and is considered to be common ancestor of the human and ape or direct forerunner of the human. Dryopithecus although ape like had arms and legs of same length and its legs and heels indicate that it must have assumed a semi – erect posture. Dryopithecus from India and Europe appear to be the ancestors of modern apes. Several numbers of Dryopithecus have been discovered from Shivalik. An almost complete lower jaw has been found in Bilaspur district of Himachal Pradesh recently. Sivapithecus is another fossil ape from shivalik hills., Australopithecus (the first ape man): The first fossil of the human like ape to be unearthed was the skull cap of a child discovered in South Africa by Raymond dart in 1924. This looked different from that of any ape or human. Dart decided that this skull cap belonged to an infant, “ape man” whom he gave the scientific name Australopithecus afriacnus from word australis meaning south and pithecus meaning ape. Since then a large number of additional skulls, jaws and limb bones have been collected from Java and South Africa. All these fossils together with some others exhibiting identical features have been grouped together in the family Australopithecine., Australopithecines were small structured averaging about 4 – feet in height. They walked nearly or completely straight. Their vertebral column has a distinct lumber curve. The pelvis was broad and basin like. Their teeth were smoothly rounded parabola, canines did not project beyond the level of the other teeth and a simian gap was absent. However Australopithecus had jaws and teeth larger than those of modern man. The face was prognathus without chin. Eye brow ridges pointed out of the eyes. Their brain capacity ranged from 450 – 600 cc or slightly more. Thus Australopithecines represented the early human with ape brain., Ramapithecus: It is supposed to be earliest man like primate and oldest of human ancestor. Its fossils were discovered from Africa as well as Asia in the rocks of late Miocene epoch ( 10 – 13 million years old). It resembled man in having erect posture and small sized canines showing that it had feeding habits similar to man., Homoerectus: In the middle Pleistocene period Australopithecines were succeeded by forms with large brains which were described as pithecanthropus. Its fossils were obtained from java by Dubois (1891), similar fossil were found in a cave in china and these were named sinotopus pekinesis. At present all these fossils are named as Homoerectus., Java man ( Homoerectus pithecantopus erectus): it existed in Pleistocene deposits some 500000 years ago. It had a cranial cavity intermediate between Australopithecus and modern man. It was more than 5 – feet tall and weighed about 750 kgs. Its forehead was low and large teeth. The chin was absent but eye brow ridges were bony. He might have learnt the use and construction of tools and how to light a fire., Pekingman (Homoerectus pekinensis) : Its fossils were discovered from caves near peking china in 1820 by Davson Black. They were very small to the java man with heavy eye brow bridges, low slanting fore head and chinless face. However their cranial cavity was much larger than java man ranging from 850 to 1200 cc., Homosapien Neanderthalenesis: (Neanderthal man), Fuhlrott discovered its fossil from Neander valley of Germany in a cave in 1856. It flourished from 34000 to 100000 years ago in Europe, Asia and North Africa. It had a cranial capacity of 1300 – 1600 cm3, sloping fore head with large supra orbital, strong mandible and semi – erect posture. Neanderthal man was cave dwellers, good hunter, used animal fur to hide their body, knew the use of tools and fire and maintained burial customs. He was the civilized man and is considered as uncle or cousin of modern man. Most probably their more advanced cousins the cro – magnon man, wiped them out., Homo sapien fossilis (cro – magnon man or early modern man): Macgregor (1868) discovered early modern man from the caves of North Italy and france. It flourished in western and central Europe. It lived 20000 to 50000 years ago and become extinct about 10000 years ago in the last glacial period (ice- age). He had a cranial capacity of about 1660 cm3, flat fore head without supra orbital ridges, erect posture, about 1.8 meters long, prominent chin and narrow elevated nose. Face was orthognathus. Cro – magnon man was cave deweller, good hunter and canvivore and made sophisticated tools (spears and arrow heads) of finely chipped stones, used fire , hides , knew painting and ivory making but did not know agriculture and domestication of animals., Homo sapiens sapiens: (modern man) It probably evolved from cro- magnon man about 25000 years ago and spread all over the world about 10000 years ago. Modern man cultured plants, domesticated animals and reached enormous population size. Agriculture probably started in Neolithic age. Thus it is concluded that man has evolved from same primitive animals although complete and continuous series of fossils are not available., Human races: anthropologists divide human into following five races according to geographical distribution and body shape and colour., Negroids: Include Africans and Australian who have black skin, wooly hair, broad nose, thick lips and dart brain- black eyes., Mongoloids: Include Asian, north and south American and New- Zealanders. Mongoloids have straight black hair, little hair on face, skin colour yellow to white or brown., Caucasoids: Include Europeans, N. Africans, N. East Asians, Arabians and Russians. This race is mostly white with wavy straight or curly hairs. This race has greatly developed in Europe and then spread to other parts of the world., Australoids: Include Australians, who have long head, prominent jaws, flat nose, dark brown skin and then spread to other parts of the world., Capoids: Include southern Africa along with Bushman and tribes man. They have yellow skin, short hair, broad face and forehead, flat nose and thick lips, ., Taxanomic positon of man:, Kingdom -------- animalia, Phylum ---------- chordate, Sub –phylum---- vertebrata, Class -------------- mammalian, Order ------------ primate, S. order ---------- anthropoida, Family ------------ hominidae, Genus ------------ Homo, Species ---------- sapiens sapiens.`, Human genome project (HGP): Each individual has a separate identity which differentiates him from the others and this identity is due to specific genetic makeup. This is why the two individuals are not similar (except monozygotic twins) and differentiate in their genetic make up. If we trace the difference between two individuals at molecular level, the differences lie in the nucleotide sequence of their DNA. This has led the scientists to prepare a detailed map of human genome and then the field of gemomics came into existence. The term genomics was coined by Thomas Roderick (1986) to describe the scientific discipline, sequencing and analyzing genome., Human genome project is a comprehensive international effort that started in the year 1990 by molecular biologists to map the entire human genome by determining the complete nucleotide sequence of DNA of each chromosome. Human genome consists of approximately three billion base pairs ( 3 × 109) , and if the cost of sequencing single base pair required about US $ 3, then the overall expenditure was estimated to be approximately 9 billion US dollars to complete the project. Besides a costly affair, the problem of storing the sequence was also challenging. This can be understood by assuming to store the obtained sequences in typed form in books. Then you need about 3300 books, each having 1000 pages and each containing 1000 letters to store the information of DNA sequencing from a single human cell., Officially the human genome project was launched on October 1, 1990 by US department of energy and the national institute of health. Soon it was joined by welcome trust U.K. By 1993 the project had become an established international effort and joined by many countries like japan, france, Germany, china etc., Goals of Human Genome Project:, To determine the sequence of the 3 billion base pairs present in the human genome., To identify and determine the functions of all the approximately 20000 – 25000 genes in human DNA., To identify and point out the specific genes that cause genetic disorders., To store the information obtained from DNA sequencing in databases., To improve the tools for data analysis., To address the possible ethical, legal and social issues (ELSI) that may arise from the project., The mega project was completed in 2003, thirteen years after it start in 1990. The information obtained from the project was more exciting. Besides providing benefits to human beings, the sequencing is also being tried about non- human organisms, such as bacteria, yeasts, Drosophila etc., Methodologies, There are two different types of approaches:, To identify all the genes that are expressed in the cell as RNA molecules. This technique is called as expressed sequence tags (ESTs)., Sequencing the total genome both coding and non- coding regions and later assigning the different regions in the sequence with specific functions. This technique is called sequence annotation., Human genome project followed the technique of sequencing the total genome. The total DNA was isolated from a cell and then broken into random fragments of relatively smaller sizes. These fragments were then closed in suitable hosts using specialized vectors. The common hosts were bacteria and yeasts. The vectors of bacteria were called bacterial artificial chromosomes (BAC) and those of yeasts were called yeast artificial chromosomes (YAC). Now a days, the technique of PCR (polymerase chain reaction) is applied for making copies of DNA fragments. The cloning resulted in the amplification of each DNA fragment so that sequencing is done with ease., After amplication, the DNA were sequenced using technique of automated sequencing. This technique was developed by Fredreick sanger (sanger is the only double noble lureate, who developed method for determining amino acids sequences in protein). Each fragment is sequenced from two ends. The sequences were then arranged on the basis of overlapping regions. Alignment of these sequences is a very complicated work which is humanly very difficult. For this purpose specialized computer programs were written to accomplish the task. A computer program identifies the overlapping sequences and joins them into one continuous stretch. These stretches were then assigned to specific chromosomes. Presently all the 22 chromosomes and X and Y sex chromosomes of human beings have been sequenced. The sequence of chromosome 1 was completed in may, 2006. Moreover , the genetic and physical maps on the human genome were generated utilizing the information on polymorphism of restriction endonuclease recognitions sites. Genome information was also obtained from microsatellites (I, e repetitive DNA sequences)., Salient features of human genome project, The total number of nucleotides bases present in the human genome is 3164.7 million., The average gene has 3000 bases, but their sizes vary greatly. The largest human gene is dystrophin, which contains 2.4 million bases., The total number of genes present in human genome in 30000. Earlier this number was thought to be 80000 to 140000 genes., Maximum number of genes 2968 are found in chromosome 1 whereas minimum number 231 are found in y- chromosome of human genome., Almost all (99.9%) nucleotide bases are exactly the same in all human beings., Functions of more than 50% of discovered genes are not known., Repeated sequences of nucleotides make up a major portion of human genome and only less than 2% codes for proteins. In repetitive sequences the nucleotide sequences are repeated many times, sometimes hundred to thousands times., The repetitive sequences are known to have no direct coding functions. They provide information of chromosomes structure, dynamics and evolution., About 1.4 million locations have been identified where single base DNA differences (called snips or single nucleotide polymorphism) occur in human genome. This information is certainly going to help to find chromosomal location for disease – associated sequences and using human history., In addition to mapping human DNA, the human genome project include mapping the genomes of species important in biological research, namely E. coli, Drosophila melanogaster etc, Application of human genome project, Mapping of the genome will :, Enhance basic understanding of human genetics., Reveal the genes responsible for diseases such as cardiovascular ailments, diabetes, cancer etc., Provide information that will help prevent inherited diseases., Lead to treatment of genetic disorders through gene therapy., Give genetic identity to us ., Help plan genetically modified diets., DNA fingerprinting, DNA fingerprinting is a technique employed to assist in the identification of individuals on the basis of their respective DNA profiles., DNA fingerprinting is also known as DNA profiling of DNA typing., Invention of DNA fingerprinting, DNA fingerprinting was invented in 1977 by a British geneticist, sir Alec Jeffereys at Leicester university. This technique was used for the first time in a regional screen of human DNA identify the rapist and killer of two girls in Narbrough, Leicestershire in 1983 and 1986., Later, this technique was refined by developing a more sensitive DNA profiling technique focusing mainly genome. Now a days, highly automated and sophisticated equipment are employed which can process hundreds of samples in a day., Principle of DNA fingerprinting, Genome (DNA of single set of chromosomes) of a person contains about three billion base pairs. These are arranged in a definite sequences to give an individual his or her identity. Technique of DNA fingerprinting is mainly based on the fact that DNA of one individual is about 90% identical to the DNA of another individual, but there is 10% of the DNA or small number of sequences that are unique among individuals to get a certain probability for a match and distinguish among the individuals., The DNA molecule can be divided into coding and non- coding sequences. The coding sequences are called exons which carry information required to synthesize proteins. The non – coding sequences , on the other hand are called introns and do not supply any relevant genetic information. The changes usually occur and accumulate within these non- coding sequences. These non- coding sequences of approximately 10 to 100 nucleotide pairs are responsible for variation among individuals and can be employed as a tool to create a genetic fingerprint of an individual. Some of these non- coding sequences contain highly repetitive sequences of base pairs. They are tandemly repeated many times and are found at many places throughout the length of DNA. The number of repeats is very specific in each individual, and it is inherited. It is unlikely that the repeats of one individual are found in the DNA of another person. For example, one individual may have the unit ACA repeated 55 times at one genome locus, 115 times at a second locus, and so on, whereas another individual is likely to have different numbers of repeats at these loci. Such polymorphic genetic loci are usually called simple tandem repeats (STRs). The identical twins however, may have the same repeats., The tandem repeats make the satellite DNA. For example, - ATTCGATTCGATTCG- sequence of bases in a DNA has a very short sequence of – ATTCG- repeated three times. Such repeated sequences are of two types ; (1) minisatellite (2) microsatellite. Minisatellite have sequences of approximately 15 to 50 base pairs and repeated tandemly upto thousands of times. There are about 30000 minisatellite loci in the human genome. The microsatellite have base pairs of less than 10 and repeated usually 10 to 100 times. In human genome, there are about 200000 such satellite loci. These simple tandem repeats of short sequences are called variable number of tandem repeats (VNTRs). These repeats are inherited from the parents, and are used as genetic markers in a personal identity test., Sources of DNA for fingerprinting, As the DNA content of a person is the same for every cell, tissue and organ, the DNA sample for fingerprinting test may be obtained from traces of blood, semen and urine stain on clothes or other surfaces. Saliva residue on cigarette buds, vaginal swab, tissue bits, or even a single hair. Besides, DNA can also be isolated from samples that are months or years old., Procedure for DNA fingerprinting, DNA molecules are isolated from a sample of blood, semen or other body fluids or tissues by using specific technique such as a high speed refrigerated centrifuge., If DNA is in poor condition or available only in minute quantities the particular STRs may be amplified by making many copies of it with the help of using polymerase chain reaction(PCR)., DNA molecules are cleaved I, e cut into fragments at specific sites with the help of a site – recognition restriction endonuclease enzyme for the purpose of restriction fragment length analysis. The DNA fragment contains the VNTRs., DNA fragments are then sorted out according to their length on an agarose gel slab by the technique called electrophoresis. The fragments get arranged along the gel according to their length and electric charges., Double – stranded DNA is now split into single strands by using alkaline chemicals., The isolated DNA fragments in the gel are copied onto a nylon nitrocellulose sheet placed on the gel. This technique is named southern blotting after its inventor E. M. Southern., Special DNA Probes are prepared in the laboratory, these contain repeated sequences of nucleotides complementary to those on VNTRs. These probes are made radioactive. The radioactive DNA probes bind to the repeat sequences on the nylon sheet. This is called hybridization. An x – ray film is exposed to the nylon sheet to mark the places where the radioactive DNA probes have bound to the DNA fragment. These places are marked as dark bands when x – ray film is developed. This process is called autoradiography., The dark bands on x – ray film represent the DNA fingerprints, or the DNA profile. A summarized account of the procedure of DNA finger printing is diagrammatically represented in figure given below., Reliability of DNA fingerprinting, The conventional fingerprints commonly used as personal identification were discovered by a scotish medical missionary Henry fauld, in 1880. These fingerprints are genetically determined , are unique for an individual and do not change in ones life. However, these fingerprints occur only on the fingers and can be altered by surgery. The DNA fingerprints occur in every cell and cannot be changed by any means. The best identification of an individual should be obtained if his/ her entire genome is subjected to restriction fragment analysis. This is not practible. Forensic DNA tests focus on only a few tiny regions of DNA. However , the DNA region chosen are ones known to be highly variable from one person to another, and give very accurate results., Application of DNA fingerprinting, In forensics, the technique of DNA fingerprinting has been widely used as a remarkable tool for solving such complicated cases where the criminal leaves no obvious traces. Under such condition , even a minute bit of persons body such as a skin follicles or a strand of hair can be used to identify the criminal by means of DNA fingerprinting., DNA fingerprinting technique is very well known for its application in paternity testing. This is because the genome of every individual is the combination of the genomes of father and mother. Every son or daughter receives half of the chromosomes from father and half from mother. Thus , a close comparison of DNA bands of a child with that of father gives direct evidences of his paternity., This technique is used to determine the extent of genetic variation in wild animals and also study of breeding patterns I,e inbreeding or out breeding. Normally, inbreeding is important for the survival of the species. The technique is also used for determining purity of these species., DNA fingerprinting is used in determining lineages of humans and other animals to ascertain biological evolution. Based on the fact that some parts of the DNA called “genetic markers” are passed from generation to generation without any change or modification, the national geographic society has launched a project to trace the path of human evolution from their prehistoric roots in Africa., DNA fingerprinting is used to diagnose heredity diseases. These diseases include hemophilia, sickle cell anemia, etc., It is matter of great concern that diseases causing bacteria are developing resistance to antibiotics. Tuberculosis is one example where the pathogenic bacteria is not responding to specific antibiotic. DNA fingerprinting is used to identify the antibiotics for which the bacterium is resistant. This technique helps in selection of the right antibiotic for treatment., UNIT – III, Biology and Human Welfare, What is health:, The health is a very frequently used by every body. Health simply does not mean absence of a diseases or say a person is physically sound or posses physical fitness. According to WHO health can be defined as a state of complete physical , mental and social well being of a person. So health has three dimensions:, Physical health: Means when all the organs and organ systems are functioning properly., Mental health: Means a state of harmony between the individual and his surrounding I,e the individual is free from anxiety and tension., Social health: Means the individual have a good job, good house to live, happy family, good neighbors and good friends. The individual shares good relations with all these persons., Characteristics of good health:, When people are healthy, they are more efficient at work. This increases their productivity and brings economic prosperity not only for the individual and his family but also for the whole society and whole nation. Health also increases longevity of people. Balanced diet, personal and public hygiene, good habits, regular exercise and yoga are important to maintain a good health., Diseases (dis = against, ease = comfort), When the functioning of one or more organs or systems of the body is adversely affected and it is characterized by various signs and symptoms , we say that we are not healthy. I, e we are suffering from a diseases and lacks comfort. Now diseases can be defined as any condition which interferes with the normal functioning of the body and affects the health is called as diseases., Immunity or diseases resistance, Every day our body is exposed to a large number of pathogens or disease causing agents but occasionally we suffer from a diseases. It is due to the fact that our body is able to defend itself from most of these pathogens. This over all ability of our body to fight against the diseases causing agent in order to protect the individual from the diseases is called immunity. This self defensive property is provided to every individual by an immune system. The study of immune system is called as immunology. Edward Benner (1749 – 1823) is regarded as the father of immunology., Types of immunity, Immunity is of two types: 1. Innate immunity 2. Acquired immunity, Innate or inborn or natural immunity: This type of immunity is acquired and inherited to an individual from parents and protects it from birth through out the life e, g human beings have inborn immunity against distemper ( a fatal diseases of dogs). Innate immunity is now specific type of defensive mechanism., Non – specific defensive mechanism: Innate immunity consists of four types of barriers which is similar for most of infections hence regarded as non – specific defensive mechanism., Physical barriers (first line defense): The skin is physical barrier of our body which prevents the entry of micro – organisms inside. The mucus membrane lining the respiratory tract, digestive tract and urino genital tract traps the micro – organisms and immobilizes them. Sebum (oil) and sweat secreted by sebaceous and sudoriferous (sweat) glands of skin make it acidic (3 to 5 PH) due to presence of lactic acid and fatty acids. Some useful bacteria of skin also produce acid and others metabolic wastes which checks the growth of pathogen on the surface of skin. This shows that skin is a self disinfecting organ., Physiological barrier: There are a number of chemical substances which kill the bacteria that tends to enter our body. The acid (Hcl) of gastric juice secreted by gastric glands of stomach kills the bacteria present in food. Tears of lachrymal glands contain lysozyme which kills the germs and bacteria. Saliva in mouth contain lysozyme that kills the germs of food. All these chemicals prevents the microbial growth., Cellular barriers ( internal defense): second line defense, The internal defense is carried on by white blood corpuscles and macrophages., Leucocytes (WBCs): Certain types of leucocytes like polymorpho – nuclear leucocytes (PMNL) especially the neutrophills have the ability to come out of the blood capillaries by amoeboid movements called diapedesis. They engulf and digest the bacteria hence regarded as soliders of the body. The process of engulfing bacteria by the cells is called phagocytosis., Macrophages: These are large amoeboid phagocytic cells which are enable to engulf the particulate material including micro – organisms, tissues debris , dead cells etc. so these are called scavangers of the body., Cytokine barriers: The virus infected cells secrete proteins called interferons. These interferons do not inactivate the virus but they make the unattaacked cells less susceptible so they are prevented from the attack of virus. They also prevents the viruses from taking over the cellular machinery. They have proved effective in treating of influenza and hepatitis., Acquired of adaptive immunity: This type of immunity is not present in an organism from the birth but an individual acquired it during its life time. When an organism suffers from an infection diseases which is caused by a pathogen which may be a microbe or a vaccine. During this encounter the protective lymphocytes of our body produces antibiotics, which not only inactivate the antigen and relieve from an infection diseases but also provide immunity against further attack. It is because of the fact that some antibody producing cells persists (remain) as memory cells for longer periods. The acquired immunity so developed may be temporary e, g influenza or permanant e,g measles , mumps, polio, small pox etc., Acquired immunity is of two types:, Active or natural immunity b) Passive or artificial immunity, Active immunity: when an organisms own cells produces antibodies it is called active immunity. This type of immunity is developed when a person suffers from a diseases or gets vaccination from a diseases e,g polio , chicken pox , mumps , measles etc., Passive or artificial immunity: in this type of immunity the ready made antibodies (gamma – globin’s) collected from other vertebrate animals which have recovered from an infectious diseases are injected into human body at the time of need. This is known as inoculation e, g person infected by rabies, tetanus , snake venom are given the sufficient amount of antibodies so that they can survive. The yellowish fluid colostrum secreted by mother during the initial days of lactation has abundant antibodies (Ig A) to protect the infant. The foetus also receives some antibodies from their mother through the placenta during pregnancy. These are the examples of passive immunity., Specific defense mechanism: (Third Line Defense ), It is not present from the birth but is acquired during the life time. It is a type of acquired immunity, which is either achieved by an organism in response to a diseases caused either by microbes or by vaccines. It is due to the presence of a powerful immune system which forms third line of defense. There are two components of immune system in the body. Humoral and cell – mediated immune system., Humoral immune system: The B- lymphocyte produces an army of proteins in response to the pathogens into our blood and lymph (body fluid humor) to fight with them. These proteins are called as antibodies. The humoral system protects the body against bacteria and viruses that enter the blood and lymph of the body. Each antibody molecule has four peptide chains two small called as light chains and two longer chains called as heavy chains. Hence an antibody is represented as H2L2.. Different types of antibodies are produced in our body are as under;, IgA: it is present in all body secretions including mothers milk and colostrums., IgM: it is largest of the antibodies but its number is small. It is first to reach site of infection. It has 10 – binding sites. It is highly effective., IgE: this antibody is concentrated in mucus membrane, skin and lungs., IgG: it constitutes 75% of the total antibodies. It can pass through placenta and is present in mothers milk. Immunity of neonate is due to it., Cell mediated immunity system (CMIS):, In this system the highly specialized cells called T- lymphocytes carry out the defensive activities. These circulate in the blood and tissues it protects the body against pathogens including the protists and fungi, which have entered the host cells. It also reacts against transplants and grafts. It also protects the body from own cells which have became cancerous., Cells of immune system, Immune system has two types of lymphocyte cells: B – Lymphocyte and T – lymphocyte., Both these types of lymphocytes develops in the embryo from yolk sac and after wards in liver and spleen. The mother cell from which these lymphocytes are produced are known as lymphocytic stem cells or hemocytoblasts which lie in bone marrow. These stem cells divide in the process of hematopoiesis and form lymphoblasts which later on produces immature lymphocytes. Some of these lymphocytes pass into thymus for further processing and maturation. Others are processed either in liver during embryonic development or in bone marrow after birth., T – lymphocytes: are those lymphocytes which differentiate and become immunologically active in thymus gland in the presence of thymosin harmone. T – cell live for 4 – 5 years. Some of them live throughout life., Functions of T – lymphocytes: like B- cells , T- cells are also antigen specific I,e different types of T- cells are stimulated by different type of antigens. Now after stimulation these T- cells divide rapidly and form a clone of T- cells. The clone has four types of cells helper T- cells , killer T – cells , suppressor T- cells and memory T- cells., Helper T- cells: they constitute 75% of total T- cells. They secrete helper factors which stimulate B- cells to produce more antibodies and increase the activity of killer T- cells. They also attract macrophages., Killer or cytotoxic T- cells: the killer T- cells reach the site of infection and after coming in contact with the microbes release perforins which cause holes in the microbial body. They also secrete toxic chemicals substances like lymphocytes which kills the microbes. They also attack cancer cells., Suppressor T- cells: they are protective T- cells which inactivate the immune system., Memory T- cells: they are those T- cells which are previously stimulated by antigens and retain this stimulation for future., B- cells: the lymphocytes which are processed in liver or bone marrow or in case of birds in the gut associated bursal lymphoid tissues ( the bursa of fabricus) a mass of lymphoid tissue near the cloaca in most of vertebrates., After wards B- lymphocytes migrate to various lymphoid tissues of the body like tonsils. Peyers patches and appendix. B- lymphocytes are connected with antibody mediated immune system (AMIS)., Vaccination and immunization, the principal of immunization and vaccination is based on the property of memory of immune system. In vaccination a preparation of antigenic proteins of pathogen or In activated, killed or weakened pathogens (vaccine) are introduced into the body. The process of administration of vaccine is called vacca. The bodies immune system is stimulated after introduction of those antigenic substances and produces a number of antibodies. These antibodies would neutralize the attack of pathogen in case of actual infection. These vaccines also generate memory B- cells and T- cells that recognize the pathogen quickly and destroy the pathogens by massive. Production of antibodies of a person is infected with deadly microbes which needs a quick immune response as in case of Tetanus, Rabies and snake bite., We need to infect the readymade or performed antibodies in order to neutralize the attack of pathogens., Types of vaccines, Vaccine ( Latin word vacca = cow). Vaccine is a liquid substance that contains dead or weakened (attenuated) antigen or a pathogen, which can be injected or taken orally to produce immunity against that pathogen., First generation vaccines: these vaccines are prepared by conventional methods involving killing , weakening or attenuation of the pathogen. They have sick effects and are not of uniform quality e, g small pox vaccine, polio, tetanus, dipthera etc., Second generation vaccination: it has been found a few antigens which are found on the surface of pathogen can stimulate formation of antibodies and can survive as a vaccine instead of the whole inactivated pathogen. Those surface antigens can be synthesized on a large scale by DNA (recombinant DNA technology ) e, g vaccine against hepatitis – B. this vaccine was produced with the help of silk worms being injected with bacculo – virus having hepatitis antigen., Third generation vaccines: these are chemically synthesized, multivalent vaccines which have highest potency and purity with the advancement of biotechnology. It is possible to produce these vaccines in the plants that may form our normal food., Human diseases, Typhoid: Typhoid is an acute infectious diseases caused by gram negative flagellate bacillus called salmonella typhi. it is the fifth most highly communicable diseases of India. Every year in India 2.5 million of people in the age group of 1 – 15 are affected by this diseases. The pathogen (bacteria) of this disease is present in the stool and in urine. So intestinal discharge and urine is highly contaminated. Typhoid spreads by through food , milk and water contaminated with bacteria either directly or through flies which transfer pathogen from contaminated stool to the edible substances that may be fruit, vegetable or only other item. It also spreads due to poor hygiene personal and public hygiene. When the pathogen contaminates to the water resources. It can give rise to severe epidemics. Some human beings can function as carriers without suffering from it. Just like Mary Mallow popularly known as typhoid Mary was one of the case. She was a cook and typhoid carrier, who continued to spread the diseases for several years through her food preparations. Incubation period varies from 1-3 weeks (average 2 weeks). The pathogen generally enters into the small intestines through food and water contaminated with them. Later on it migrates to other organs like spleen , lymph nodes , payers patches of ileum through blood. The multiplication of bacterium occurs within the phagocytic cells of these organs. The bacterium releases toxins which causes high fever in steps in first instant. Later on it becomes sustained high fever of 1020 to 1040f or 390 to 400c., The common symptoms of this disease are weakness, loss of appetite, stomach pain , headache, gastro-intestinal disorder like lesions and ulceration in the intestinal wall, which in severe case may lead to intestinal perforation and death. There is diarrhea which becomes hemorrhagic. A rose colored rash may occur on the upper abdomen at the end of the first week., Vaccination provides immunity for 1-3 years. Antibiotics like ampicillin and chlorophenols are standard and effective drugs against typhoid. The resistant cases are treated with quinoline derivatives like ciprofloxine and ofloxcin. The treatment should be prolonged as the patient may continue to pass the bacterium even after recovery. It may reach again., Prevention: Proper sanitary disposal of human faeces. Personal hygiene, washing hands with soap and disinfectants after toilet and before eating anything. Public hygiene includes screening of all water resources and food sources. Proper and timely immunization of infants in case of epidemic situation and adults., Hepatitis: Hepatitis is an acute world wide communicable diseases that attacks both children and adults throughout the year. It may prove fatal. Hepatitis is the viral infection of liver causing its inflammation. It is accompanied by following symptoms: Loss of appetite, nausea , whitish stool, vomiting, diarrhea, cough and cold and pain in abdominal muscles, orange brown urine and jaundice ( yellow colorations of skin and pupil). Hepatitis is of various types; hepatits – A, hepatitis – B, hepatitis – C, hepatitis – D, hepatitis – E and autoimmune hepatitis., Hepatitis – A: It is caused by hepatitis – A virus. Formerly it was known as infective hepatitis. It is an acute infection of the liver. It is more common in children and young adults with an incubation period of 2 – 6 weeks. It is caused by hepatitis – A virus which is transmitted from person to person by ingestion of contaminated food or water or through direct contact with an infected person. Millions of individuals are infected with ( HAV) each year. The cause of the diseases is poor sanitation. The disease can be prevented by proper sanitation disposal of human faeces, with maintenance of personal and public hygiene and proper vaccination especially in case of epidemics. Hepatitis – A vaccine has been proven effective in controlling out break world wide. The vaccine provides protection for 20 years., Pathogenesis: Following ingestion through contaminated food or water , the virus HAV enters blood stream through the epithelium of oropharynx or intestines. virus multiplies within the hepatocytes and kuffer cells. The virus damages the liver cells and causes inflammation of liver and juandice. Virons are released into the bile and excreted with stool. Presence of IgG antibody means that the acute stage of the illness is past and the person is now immune to future infection. These antibodies are also found in blood after vaccination., Hepatitis – B or serum hepatitis, It is caused by hepatitis – B virus (HBV). HBV is known as blood born virus as it occurs in blood. It is transmitted from one person to another via blood. It is also transmitted from infected mother to child during or shortly after the birth. Semen which contains small amounts of blood or saliva that is contaminated with blood also carries the virus. Virus may be transmitted when these fluids come in contact with the broken skin and through many membrane of mouth and urinogenital tract of an infected person. High risk group includes:, The man/woman involved in multiple sex partners., Persons suffering from STDs., Drug users who share needles and syringes., Infants born to infectious mothers., Health care workers who stuck with needles and soaps, instruments contaminated with blood., Infants born to infectious mothers in a number of cases mode of transmission is still unknown., Diagonosis, HBV is diagnosed with blood tests. These test can detect pieces of virus in the blood. (antigens , antibodies against the virus and viral DNA). Blood tests of HBV are then done. When routine blood tests show abnormal liver functioning or if a patient had a large amount of vomiting and not able to take in fluids. Other tests include C.T scan or USG. HBV vaccine is available for the diseases., Treatment, Acute HBV usually resolve in its own and does not require medical treatment and if very serve symptoms such as vomiting or diarrhoea are present than the affected person may require treatment to restore the electrolyte balance. There is no medication that can prevent HBV from becoming chronic. The chronic patient should see their health care provides regularly. Antiviral drug stop the virus from multiplication and is effective., Prevention: In addition to HBV- vaccine other ways to protect yourself from their dreadful diseases which is 100 times more infections than AIDS virus (HIV) includes:, Abstain from unusual and multiple sex partnership., Do not share needles or syringes., Do not share anything including grooming products that might have blood on it just like razors, tooth brush., Health care workers should adopt productive measure which handling their job., Hepatitis c: it is caused by Hepatitis C virus. Mode of transmission same as that of hepatitis B., Hepatitis D: it occurs in those persons who are suffering from hepatitis B., Hepatitis E: it is caused by hepatitis E virus. Mode of transmission like hepatitis A., Malaria, Malaria is one of the most common diseases of mankind. It is more common in tropical and sub tropical countries especially in Africa and Asia were millions are infected. It is responsible for the death and reduced resistance in large number of persons every year. It is the most common protozoan diseases caused by the plasmodium a tiny protozoan. Different species of plasmodium are ( p. vivax, p. falciporum) are responsible for different types of malaria. Among these types plasmodium falciparum is malignant malaria the most serious form and proves fatal., Life cycle of plasmodium is digenetic (two hosts) with man secondary host and female Anopheles (primary host)., Schizogony: Plasmodium enters the human body as sporozoites (infectious form) through the bite of infected female. Anopheles mosquito along with a drop of saliva. These sporozoites initially multiply within the liver cells and then attract the red blood cells (RBCs) and rupture them. The heam of hemoglobin in these ruptured RBCs is changed into a toxic substances hemozoin which is responsible for the malaria attack with chill and high fever which reoccurs after every three to four days. It is the asexual phase known as schizogony which is completed in man., Gamogony: It is the phase of sexual reproduction of the parasite which is partly completed in man and partly in the stomach of the mosquito. The merozoites enter into the fresh RBCs when they are changed into two types of gametocytes. Micro and macrogametocytes further development occurs only when these gametocytes are sucked by female Anopheles mosquito. In the stomach of mosquito the gametocyte from two types of gametes sperms and ova. Fertilization also occurs in the stomach of mosquito and zygote is formed. As sexual reproduction occurs in the mosquito so it acts primary host while man acts as secondary host., Sporogony: it is the phase of asexual multiplication which occurs in the mosquito. During this phase the zygote changes into a rounded oocyst inside the stomach it feeds, grows and undergo multiple fission to form a large number of sporozoites. The oocyst ruptures and sporozoites are released. Most of the sporozoites enter the salivary glands and wait to be injected into another man., Symptoms: malaria attack is characterized by headache, nausea and muscular pain. Total period of malaria is of 6 to 10 hours that can be divided into 3- stages., Cold stage chill and shivering., Hot stage rises to 1000c faster respiration and heart beat., Sweating stage: there is perspiration and gradual fall in temperature. Malaria results in anaemia and enlargement of spleen and liver. The patient feels weak and exhausted., Prophylaxis:, Wire gauzing of doors, windows etc to check entry of the mosquito., Use of insect repellants to prevent mosquito bite, sleeping under mosquito, nets., Killing of mosquito larva by filling small sized ditches etc. with soil or sprinkling kerosene oil on large sized water body or introducing larvicidal fishes e, g Gambusia, trout’s , birds (ducks) and plants., Killing of adult mosquito by spraying of insecticides like DDT (dichlorodiphenyl trichloro ethane )and BHC (benzene – hexa – chloride)., Therapy:, A number of anti – malarial drugs and available e,g quinine, choloquin, paludrine, atabrine. Most effective drug is daraprim which kills the parasitic stages present in both liver cells and RBCs of blood. Latest anti- malarial drug is mefloquin., Filariasis (elephantiasis), It is a helminthic diseases which is caused by a number of worms. But in India it is caused by two worms namely wucheria brancrofti and wucheria malayi commonly called filarial worms. There are found in lymph vessels and lymph nodes of man (especially of lower limbs). So man serve as the primary host. As the diseases is identified by the chronic inflammation of lower limbs (swelling) of the legs, scrotum and other parts. This diseases is commonly called as elephantiasis(resemblance with the legs of elephant). The pathogen is spread from one individual to another through mosquito like culex and to a less extent by Anopheles and Aedes. It also passes same stage of its life cycle in mosquito in human beings. Its incubation period is 5 – 8 months. The adult worms (parasite) resides in lymph vessels, connective tissue and mesentery. They are thread like and shows sexual dimorphism I, e females are longer than males. In the lymphatic system they produce youngones called microfilaria which are microscopic(2.5mm) and are found in blood and reach the skin during night. When a mosquito sucks blood from an infected person. The microfilaria which are harm less to man enter the stomach of mosquito(secondary host). Further development occurs with in the mosquito in about 10 to 20 days these microfilaria from infective larva which are now found in the mouth parts of mosquito. When this mosquito bites any person the larva are deposited on the skin from there they make their entry into the skin and finally enter into the lymphatic system where they develop into adults and causes the diseases., Symptoms, It is characterized by fever, proliferation of endothelial cells and deposition of metabolites on the walls of the lymph vessels. This causes enormous swelling of certain body parts like legs, sacrotal sacs , breasts due to blockage of lymph vessels., Control and prevention, The diseases can be cured by drugs like hetrazan and diethyl carbamine (DEC)., Reconstruction of affected body parts through surgery., Prevention from mosquito bites., It is also advisable to take prophylactic drugs in filarial prone area., Ascariasis, Ascariasis is caused by an intestinal endoparasite of man Ascariasis lumbricoids commonly called as round worms. This diseases is more common in the children because of unhygienic feeding habits. Life cycle of ascariasis in monogenetic I,e life complete within only single host. Sexual dimorphism occurs in Ascaris. The male is smaller in size with curved posterior end while as female is longer in size and straight in posture. Fertilization is internal and the female lays the capsulated eggs along with the faces of infected person. A female worm produces about 2 – million eggs per day. They come out along with faeces. Each egg contains a juvenile worm which takes 20 – 24 days for forming infective stage (second stage juvenile) I,e embryonated egg., While the first stage juvenile (Rhabdiform) is now infective., Transmission, The diseases generally spreads through improper disposal of human stool, which contains round worm eggs. When this stool is passed on open land / soil it contaminate vegetables growing on it. It can contaminate food articles, taps, soaps and other articles. Dirty hands can spread the diseases directly., Symptoms, Ascariasis is characterized by abdominal pain, indigestion, weakness, anaemia, nausea, vomiting, diarrhoea etc. heavy infection may cause blockage of intestines, juvenile worms may damage the brain and liver and can cause pneumonia. Appendictis may also occur due to injury to appendix., Diagonosis, It is diagonised by stool test. Dermal test or scratch test., Prevention/control:, Proper and sanitary disposal of human faces., All edible fruits and vegetables should be washed properly., Proper coverage of eatables from vector( flies) etc., Washing hands before eating anything., Therapy, Main anti ascaris drugs are piperazine, hetrazan, chenapodium oil and tetrachloro ethylene., Common cold, It is one of the most common infectious human diseases which is caused by a group of viruses called Rhinoviruses. Human infection is air born , it also occurs through droplets infection or through contaminated objects like pens, books, cups, computer parts, towel etc. incubation period few hours to a few days. The pathogen do not reach the lungs. They infect nose and upper respiratory tract and causes inflammation of mucus membrane. It causes infection of nasal tract, nasal congestion, flow of mucus, sneezing, sore throat, hoarsness, cough, tiredness, headache, slight fever. Some persons also suffer from allergic rhinitis. Its attack lasts for 3 – 7 days., Prevention, Isolation of the patient till recovery., Sterilization of the articles and clothes used by the patients., Therapy, It cures automatically after 3 – 7 days. Medicines are taken to reduce severity of nasal irritation., Amoebiasis, Amoebiasis is caused by an intestinal endoparasitc protozoan of man Entamoeba histolytica. It is found in large intestine and lower parts of small intestines. The diseases is wide spread in India because of poor sanitary conditions and unsafe drinking water. It is estimated that 10% of world population is affected by this diseases., Transmission, Cysts of Entamoeba histolytica present in the stool of infected person is the source of infection. Some animals become vectors and carry the infection ( house flies, cockroachs, cat, dog, rats etc). faulty disposal of human faeces pollutes the drinking water, vegetables, fruits and other edibles through the agencies of flies, insects or air currents., A cyst is viable for 3 – months incubation period. Diseases can occur at any stage., Inside the intestines the cyst which gained entry through contaminated food germinates and releases right entamoeba. The parasite secretes an enzyme called cytolysin which dissolves the wall of intestine. The parasite reaches blood capillaries and feed on red blood corpuscles. The parasite causes necrosis or small ulcers in the intestinal wall. Pieces of this ulcerated mucus membrane, mucus and blood pass on along with the faecal matter. In case of serve infection the parasite pass into blood stream and enter various body organs like liver, lungs, spleen and brain and causes pus filled abcesses., Symptoms: The diseases shows symptoms like :, Abdominal pain, Mild diarrhoea alternating with constipation., Passing out of mucus and blood., Faeces having cysts., Diagnosis’: blood stool and presence of tetranucleate cysts in the faeces., Prevention: sanitary disposal of human faeces, safe drinking water, hygienic kitchen practices of food against flies, proper washing of vegetables , fruits and salad. Avoiding hand washing and bathing in village ponds, springs etc. Health education , proper toilet habits., Therapy: antibiotic like teramycin, erythromycin, aureomycin and most effective drug is metronidizole against amoebic dysentery., Ringworms (dermatophytosis), Many fungi belonging to the genera Microsporum, Trichophyton and Epidermatophyton are responsible for superficial fungal infection of skin called as ringworms. It is one of the most common infectious diseases of man. The diseases is characterized by the appearance of dry skin, scaly lesions occur on various parts of the body such as skin, nails and scalp. These lesions are accomplished by intense itching, heat and moisture help these fungi to grow – especially in skin folds ( e,g groin, between toes). Ringworms are generally acquired from soil, or by using towels, clothes or even the comb of infected individuals. Maintenance of personal and public hygiene is very important for prevention and control of diseases., Cancer( Gk; karkinos – malignant, latin crab- tumor), Cancer is one of the most serious diseases of human beings and known as one of the major killer diseases all over the globe. According to an estimate 10 million people are diagnosed as having cancer every year through out the world. It causes 4 – million deaths annually at world level(WHO report). More than a million Indians suffer from cancer and a large number of them die from it annually. In our body cell growth and development is highly controlled and regulated. In cancer cells a breakdown occurs in this regulatory mechanism. Normal cells show a property called contact inhibition I,e their contact with other cells inhibits their uncontrolled growth. Cancer cells appear to have lost their property. Hence cancerous cells continue to divide in an uncontrolled manner. So cancer is a group of diseases which is characterized by uncontrolled division and proliferation of cells. These proliferated cells have the ability to invade other tissues and parts of the body. Due to uncontrolled growth and division of cells a mass of cells called tumor (neoplasm) I,e new growth is generally formed. However all tumors are not cancerous and no tumor is formed in leukemia (blood cancer)., Tumors are of two types:, Benign or non malignant tumors, Benign tumour is non cancerous and non malignant tumor. It remains confined to the original place where it is formed. It stops increasing in size after certain growth gets encapsulated in connective tissue so that it is unable to infiltrate into the adjacent tissue e,g warts it may however cause discomfort or pain as it passes other tissues., Malignant or cancerous tumors, It is the actual cancerous tumor which grows rapidly because the dividing cells continue proliferation. They invade and damage the surrounding normal tissues. They also starve the normal cells by occupying their vital nutrients. As they are not encapsulated its cells reach other parts of the body through blood and lymph and where ever they get lodged in the body they start a new tumor there. This property is called metastatis. It is the most feared property of malignant tumors., Causes of cancer, Etiology is the study of causes of a diseases. The causes of cancer are not fully understood. It is neither contagious nor a heredity diseases. However many factors are known to favour the development of cancer. These factors are called carcinogenic agents or carcinogens. The causes of cancer are briefly described under the following headings:, Ionizing radiations, Like x – rays , gamma rays and particulate radiations from radioactive substances are known to rupture DNA strands and induce mutations to cause oncogenic transformation I,e change proto – oncogene into oncogene and cancer e,g excessive exposure to sunlight may stimulate skin cancer in farmers. Radiologists suffer from leukemia about ten times than physicians. Even non ionizing uv radiations cause DNA changes and leads to cancer., Physical irritants, Repeated friction or irritation by certain foods causes continued abrasions of the linings of the intestinal tract are also carcinogenic. Kangiris is known to cause abdominal skin cancer due to constant heat exposure., Chemical agents, Several chemicals are carcinogenic. These are caffeine, nicotine, products of combustion of coal and oil and pesticides. Hormones like testosterone and estrogens are known to cause prostrate and breasts cancer. Cigratte and cigar tobacco smoking causes mouth , lip and lung cancer due to presence of benzopyrene and N- nitroso – dimethylene. In animals fat rich diet is known to cause cancer of large intestine. Dye workers using aniline dye have high rate of bladder cancer., Biological agents: certain viruses are known to cause cancers, they are known as onco – viruses e,g Epstein – Barr virus, Herpes simplex – type viruses., Mode of action of carcinogens, Different carcinogens act in different ways and on this bases are divided into three categories:, Some carcinogens agents cause oncogenic transformation. it is suggested that every individual passes some inactive cancer causing genes called proto – oncogenes or cellular – oncogenes ( c- one ). These carcinogens cause changes in the genetic material DNA which transform these proto –oncogenes into active oncogenes. These gene mutations cause loss of normal control mechanism and cells undergo abnormal cell growth and cell division., Tumor promoters: These agents promote the proliferation of the oncogenically transformed cells and include certain growth factors and hormones e,g testosterone act as a tumor promoter in prostrate cancer., Oncoviruses: These are cancer causing viruses and may be DNA or RNA viruses e,g Epstein – barr virus, Herpes simplex type of virus etc., Types of cancers, On the basis of their original tissue from where they arose, tumours are of three types:, Carcinomas: The cancers which are located in epithelial tissues and glands e,g cancer, stomach cancer, lung cancer, skin cancer, pancreas cancer etc. cancer of epithelial glands is called Adenoma. These form 85% of all cancer types. Melanomas cancer of melanocytes of skin., Sarcomas: The cancers which are located in connective tissue and muscular tissues derived from mesoderm are called sarcomas e,g cancer of bone, lymph nodes and muscles. These are called lymphomas. It affects the lymphatic system. Osteoma cancer of bone and lipoma cancer of adipose tissue., Leukemia (blood cancers): They are characterized by abnormal increase of white blood corpuscles count (WBCs) due to their increased formation in the bone marrow (200000 to 1000000 mm3). It is the most common type of cancer below 15 – years of age. Bone marrow transmission is recommended., Danger signals of cancer, There are a number of symptoms which indicate the signals of cancer. Cancer can be treated if detected in early stages. Therefore one should consult a doctor immediately if these symptoms are found., Presence of persistent lump or thickening which can be felt by touch in lip , tongue ,breasts etc., Any wound that does not heal in normal time., Persistent indigestion and difficulty In swallowing of food., Sudden and rapid change in appearance , form and growth of some warts on the body., Persistent change in bladder and bowl movements., Unexpected loss of weight., Excessive bleeding in menses in woman or loss of blood outside the normal date., Any wound with continuous bleeding from skin , mouth or other opening of body., Diagnosis of cancer, Early detection of cancer is essential for the successful treatment of the diseases. Cancer detection involves the biopsy and histological examination of the affected tissue. Blood and bone marrow tests for increased cell counts is case of leukemias. In biopsy, a piece of the suspected tissue is cut into thin sections is stained and examined under microscope (histological studies) by a pathologist. Techniques like radiography use of X- rays , CT (computed tomography) and MRI (magnetic resonance imaging) are useful in the detection of cancers of internal organs like kidneys, liver, pancreas etc. mammography is used for detection of breast cancer. Monoclonal antibodies containing radioisotopes are used for determination cancer specific antigens. Certain genes predispose individuals to particular cancer. Identification of such genes can be carried out with the help of PCR – (polymer chain reactions) and southern blotting. Such individuals can be advised to avoid exposure to those particular carcinogens e,g tobacco smoke for person prove to lung cancer., Treatment of cancer, The common approaches for treatment of cancer are surgery , radiation therapy and immune therapy., Surgery: It involves the removal of cancerous parts preferably non – malignant by operative methods. It can be employed against all cancer types like leukemia. It simply reduces the tumour load before starting other therapeutic methods., Radiation therapy: In this method the cancerous parts are exposed to ionizing radiations like x – rays which kill the cancerous cells. It gives good results in lip , mouth , skin and cervical cancers. This method is employed to 80% of cancer patients but causes damage to the normal tissues present very close to the cancerous tumour., Chemotherapy: A number of chemicals like mercaptopurine , 6 – aminopterin are known to kill the cancerous cells. Catharanthusroseus commonly called sadabahar provides two anti – cancerous drugs vincristin and vinblastin which are used against leukemia drugs have side effects like hair loss , anaemia etc., Immunotherapy: It is the latest methodology of cancer treatment in which the natural anti – cancer immunological defense mechanism is strengthened e,g in radio immune therapy radio isotopes linked monoclonal antibodies are used for the treatment of cancer. Y – interferons are used as biological response modifiers which when given stimulate the immune system and help in destroying the tumour., HIV and AIDS, AIDS: the word AIDS stands for acquired immune deficiency syndrome., A = acquired means must do something to get it., I = means ability to fight against infectious agents., D = deficiency means lack of, S = syndrome means cluster of symptoms that are characteristics for a diseases., This means that AIDS is deficiency of immune system which is acquired during the life of an individual so it is not inborn or congenital diseases. AIDS is a severe viral diseases which has been able to overcome all the defensive mechanisms of our body and generally leads to death. It is caused by the human immune deficiency virus (HIV). The HIV is a member of a group of viruses called retrovirus., Structure of HIV: It is rounded retrovirus of about 100 mm in diameter. Its surface is covered by a host derived envelope which bears spikes with glycoprotein (gp 120) capable of recognizing CD-4 or T- 4 antigen receptors found on helper T- cells , macrophages and nerve cells inner to this envelope viral wall made of two coverings an inner covering or capsid of p-24 and an outer covering or capsid of p – 18. The core contains two single strands of genomic RNA associated with an enzyme reverse transcriptase. The first AIDS case was reported in USA in 1981 . virus of AIDS was first isolated and identified by prof. Luc, In india AIDS virus was first reported in 1986 among ten prostitutes in Chennai. According to UN AIDS report (july 2000) HIV population in india was as high as 4.1 million with second highest HIV population in the world after south Africa. In india AIDS infection is rising at the rate of 10%. So india is known as world capital of AIDS., Mechanism of action of HIV virus, When HIV enters into the body it passes to all parts of the body through blood and enter body fluids. When ever it comes in contact with a macrophage , it binds with them. This binding occurs between gp 120 of a viral spoke and CD4 receptor of the macrophage. HIV enters the macrophage through endocytosis. The protective coat or cover (protein coat) is shed RNA and reverse transcriptase floats in the cytoplasm. The viral RNA synthesizes DNA in the presence of reverse transcriptase enzyme. This viral copy of DNA is incorporated into hosts DNA to form a prophage (provirus). It replicates along with host DNA. The duplex (viral + host genome) directs the host to form a genomic RNA and mRNA to synthesize viral protein including reverse transcriptase. Genomic RNA and proteins are packed together to form virus. Several copies of virus are formed. They do not kill the macrophage bud off from it through exocytosis. A large number of viruses are formed which attack further macrophages in order to increase the number. During reverse transcription in macrophage some mistakes may occur which results in mutation. HIV is considered the most mutable virus. Changes also occur in gp120 of the spikes which do not allow it to contact with CD4 or CCR-5 but instead CXCR4 which are found only on the surface of the Helper T- cells. Later HIV virus multiplies in the same way inside the helper T- cells and reduces their number. Drastic reduction in the no. or T-lymphocytes weakens the immune system of the body so that opportunistic infection begin to invade the body. It is the onset of AIDS., Modes of transmission, The HIV virus only transmission from an infected partner to a normal I,e from man to women , woman to man or man to man. Sharing needles, syringes , shaving razors , contaminated with blood , use of contaminated hypodermic needles and syringes by drug abusers., Contaminated blood transfusion: blood transfusion without HIV screening tests from professional donors can spread the diseases., Mother to child: HIV mother may spread infection through placenta at the time of birth due to rupture of blood vessels. Breast feeding is also one of the factor for transmission in case of HIV mother. HIV/ AIDS are not transmitted through casual contact like hugging, dancing , sneezing , talking , touching or shaking hand with an HIV person. By sharing food , utensils , towels , bedding or clothes HIV is not transmitted. It is also not transmitted by biting of mosquito or bed bugs. Hence it is imperative for the physical and physiological well being that the HIV/AIDS infected persons should not be isolated from family and society. There is always a time gap between the infection and the appearance of the AIDS symptoms. This period may vary from a few months to many years usually 5 – 10 years., Diagnosis: AIDS can be diagnosed by ELISA test and western blot test., Symptoms, HIV attacks helper T – lymphocytes and reduces their number below 200 in comparison to 500 – 1500 in a normal person. So it is a disorder of cell mediated immune system of the body. So the patient becomes prone to opportunistic infection whose symptoms are unexplained weight loss, low grade fever, cough , nausea, night sweating , ulceration of mouth, tuberclousis, enlargement of lymph nodes and brain damage., Prevention of AIDS, As AIDS has no cure, so prevention is the best option. HIV infection more often spreads due to conscious behaviour and is not something that happens unconsciously or itself like pneumonia or typhoid. The only excuse with this dreadful diseases may be ignorance. It is our country national AIDS control organization (NACO) and other NGOs are doing a lot to educate people about AIDS. The main aim of this awareness and education is not allow the people to die of ignorance. WHO has launched a no. of programmes in order to control AIDS which includes making blood from blood banks safe from HIV. Ensuring use of only disposable needles and syringes in public and private hospitals. Avoiding unsafe sex controlling drug abuse. Every year Dec – 01 is recalled worldwide AIDS day., Therapy and treatment, Till today there is no specific treatment or therapy available against HIV infection although Azido thymidine (AZT) has been found to suppress AIDS virus but it causes anaemia. TIAS prevents proliferation of AIDS virus. Though 43 vaccines has been developed by USA and many are in different stages of testing but none has proved effective. However these vaccines may not be appropriate for the Indian strains. So developing a vaccine is our top priority., Insects and human welfare, Sericulture: The art and science of breeding, rearing, care and management of silkworms (Bombyx mori) for the production of silk is called sericulture. The sericulture is an important cottage industry. Now it is considered one of the largest industries in china, japan , India and some European countries where silk worm is reared on mulberry leaves on commercial scale to get raw silk from the cocoons of the moth., The fertilized eggs of silk worm moth are placed on the leaves of mulberry plant. These eggs hatch out within a few days into creamy white rapidly moving caterpillar. These caterpillar voraciously feed on the fresh mulberry leaves and soon undergo a fast growth. Now they are popularly called as silk worms. These silk worms possess silk glands. They secrete a sticky secretion from these glands, which is spun around the worms to form a hard covering of silk fibres. The resultant structure is called as cocoon. The silk worm along with cocoon is known as pupa., The pupa are killed either by drying them in sun or by boiling them. Then the raw silk is extracted from the cocoon by reeling out the silk threads. The pupa are killed other wise the adult silk worm moth will emerge out from the cocoon by breaking it, which will yield the silk broken into short threads. However few cocoons are kept and are allowed to develop into adults as seeds in order to continue the generation. The silk worms are destroyed in large no. by a severe heredity diseases known as pebrine which is caused by a parasite protozoan Nosema bombycis. Nosema infects the eggs of the silk worm and transmits the diseases from one generation to another. This diseases is characterized by the symptoms that caterpillars brownish or pale and finally die. The best protection from the diseases is prevention. The body fluid of the mother should be analyzed for Nosema germs. The infected mother should be destroyed in order to check the spread of diseases. Proper and safe hygiene methods should be adopted during the rearing process for best production and good yield of sick., Bee keeping or Apiculture, The art and science of rearing, care and management of honey bees for obtaining useful substances like honey and wax is called apiculture. The four important species of honey bees occur in India, but one of them is exotic and is normally grown in bee boxes or artificial hives. It is Apis melifera(Italian or European bee). It yields a good quality and quantity of honey. Other three species are indigenous. They are Apis dorsata(rock bee) and Apis flora(little bee). The honey bee is a colonial , social and polymorphic insect. It lives in nests called hives. A natural hive or nest of honey bee consists of vertical sheet of wax having a no. of hexagonal cells on its sides for rearing young ones(brood cells) storing honey(storage cells), royal chambers for queen and chambers for workers. Honey bee has three casts or bees. The gravid female or queen , male or drone and workers. Each member performs its assigned job. The queen secretes an antiqueen substance or pheromone from its mandibular glands. It inhabits the workers bees not to build any brood chamber for further queen or feed any larva on royal jelly. Queen receives all the sperms which it requires for its life time during the nuptial flight., They are stored in spermatheca. Eggs are hatched within three weeks. When the new queen is ready for its nuptial flight , the old queen along with numerous workers left the hive and settles down at a safe place and build hives. It is called bee swarming., The male members which develop from unfertilized eggs are called drones. They are meant for copulating with virgin queen during nuptial flight. Afterwards , they are not allowed to return back to the hive. Worker bees are sterile females which are meant for maintaining the colony. They build the comb, collect the nectar. Pollens feed and care about the young ones. They secrete royal jelly from their hypopharyngeal glands. The wax is secreted by a pair of wax glands which are placed ventrally on the abdomen. The nectar collected by the honey bee is temporarily stored in its crop. The salivary enzymes convert the sucrose of the nectar into glucose and fructose. The later is regurgitated (taken out) from the crop into cells of the comb, where it is concentrated by evaporation and becomes the honey., An artificial hive or bee box has a brood chamber placed on a wooden platform with an opening for the entry and the exit to the bees at the bottom. A no. of frames coated with wax sheets having hexagonal imprints are placed in the chamber vertically with the help of wires. The bees start making cells along the margins of hexagonal imprints. Each wax sheets provide a foundation for the bees to build combs or both the sides. When honey chambers get filled with honey the bee box is smoked in order to anaesthise the worker bee. Honey frames are taken out and placed in centrifuge honey extractor. After extraction of honey the frames are replaced., Diseases and pests, Two common diseases are; nosema caused by protozoan Nosema apis and Acrine caused by mite Acrapis woodi. Pests of honey bee are king crow, green bee – eater, black ants etc., Poultry farm management, Poultry farm management is the branch of animal husbandry which is concerned with rearing, breeding and caring or poultry birds for production of meat and eggs. Poultry is a class of domesticated birds which includes chickens, ducks , turkeys, guinea and some breeds of pigeon. More than 90% of poultry farming is based on chicken or domesticated fowl (Gallus domestics). The egg laying birds are called as layers, while as the meat yielding birds are called as broilers. In India annual production of broilers is 1.5 billion and that of eggs is 47 billion eggs. Now India ranks third in poultry production throughout the world(2009). Andra Pradesh is largest egg production state., In india poultry has registered the highest growth rate among all sectors of agriculture in the last two decades. It is mainly due to rapid increase in poultry population density and introduction of birds with the fastest growth , diseases resistant and environmentally friendly properties. India breeds of chicken are Aseel. It provides high yield of meat ( average weight of cock is 4 – 5 kgs) while that of hen is 3 – 4 kgs., Exotic breeds include the white leghorn. It is a good layer and produces large sized white eggs. It is small sized and needs less feed in comparison to indigenous breeds. But it is not ideal for heat., Rhode island red, It was developed on the farm of Rhode island in USA. It is reared for dual purpose I,e both for meat and eggs., Poultry birds are kept in proper poultry sheds which are constructed lengthwise from east to west and away from residential areas. It should be properly ventilated and protected from rats, snake, cats and dogs. The floor of the shed is constructed in a sloping pattern and is covered either by 10cm thick litter of paddy husk, saw dust by crushed grass or maize cobs etc. it should be provided with electricity and running water. The shed should contain enough space in order to avoid overcrowding. The birds should be separated as per age and category. Broilers needs to be separated from layers., Feeding: Poultry feed consists of the inferior quality of grains , bran of rice and wheat, oil cakes , fish , meat , green residue of vegetables , salt , vitamins and minerals. Grown chickens called growers need a balanced feed containing carbohydrates as energy soruce proteins and fats., Diseases of poultry: Poultry birds are vaccinated against various fatal infectious diseases which causes huge loss during an outbreak of diseases. This vaccination is available against some common diseases like fowl cholera (bacterial), fowl pox (viral), respiratory mycoplasmosis (PPLO) , candidiasis (fungal) and raniket (viral). Ectoparasite like lice, mites and ticks can be controlled by spraying insecticides like melathione. Endoparasites like Taenia (tapeworm) and round worms can be controlled by wormicides. Fungal diseases like mycosis can be controlled by using Bordaeux mixture, bacterial diseases can be controlled by sulpha drugs and antibiotics., Bird flu: It is an Avian influenza which can also attack human beings. It is caused by H5N1 influenza virus. In 1918 it attacked human beings and killed about 50 million human. The diseases appeared in 1977 from Hong kong, 2003 from Thailand and 2008 from Bengal. The reservoir of bird flu seems to be migratory birds e,g bar headed geese. This virus attacks and kills the monocytes. It can undergo repeated mutations so that no safe vaccine or medicine is available. The pathogen is air borne. Therefore poultry workers have to be extra careful. The raw meat and eggs may contain virus but cooked ones are free from virus. Poultry farming helps to raise the nutritional standard by supplying meat and eggs., Whole liquid egg consists of 36% yolk, 64% proteins (mainly oval albumin , vitelline phophovitin etc ) and certain vitamins like ribo flavins. Poultry meat contains proteins like myogen globulins , fats , minerals etc., Dairy farming, Animal husbandry: the science of systematic breeding , feeding and control of diseases of domesticated animals is called animal husbandry. The domesticated animals which are raised for use or profit are collectively called livestock. Which includes buffalo, cow, goat, sheep, camel, horse, poultry and fishery. Bees and silk worms are also considered as components of animals husbandry. However more accurately the term livestock is used for farm animals., Management of farm and farm animals, Farm management is the controlled and scientific handling of the farm animals in their rearing , grooming, breeding and caring so as to yield a good production. It ensures proper and balanced feed, clean drinking water, a proper shelter , grooming , immunization , care of skin and selective breeding., Diary farm management, Diary is an establishment dealing with milk and milk products. Diary animals are mainly cows and buffaloes which are reared for obtaining milk. Diary farm management deals with processes and system which increases yield and also improve the quality of milk. Yield of breeds in farm. The selected breed should be high yielding with a longer lactation period, diseases resistant and suitably adjusted with the local climatic conditions of the area. A good animal shelter is also an important aspect of farm management. It not only increases the production of milk but also improves the health of the animals as well. A good shelter should protect the animals from harsh climatic conditions and also from other animals. It should be properly ventilated with clean drinking water facilities. It should be spacious and provide enough space for each animal to stay comfortably. It should have a slopping floor for the hygienic disposal of animal excreta., Indigenous breeds of cattle: A breed is a group of animals which are related by origin and are similar in most of morphological characters like appearance , size, configuration etc. in India there are about 30 indigenous desi or Indian breeds of cows and ten breeds of buffaloes. Depending upon the utility , the cattle’s are classified into the following groups:, Milch breed: These cows are high milk yielding but their bullocks are not very useful as work animals e,g Gir (Gujrat), sahiwal (Punjab) , Red sindhi etc. sahiwal is most superior among others., Draught breeds: Their males are strong and beasts of burden ,used for ploughing of land and transporting of materials but their cows are less milk yielding e,g Nageri, Hallikar and malwi., Dual purpose: Their cows are good milk yielding and males are good work animals e,g Deoni, sahiwal , tharparker and Dangi. A no. of exotic breeds have also been brought into India e,g Holestein – friesien breed of Holland yield 3200 litres / year milk., Jersey of island of England, Brow swiss of Switzerland, Red dan of Denmark., Feeding of cattle: The feeding of cattle should be carried is a scientific manner. In order to maintain good health and increased yield cattle should be given a balanced feed containing both roughage and concentrate in adequate proportions. A cow daily needs 15 – 20 kgs of fodder(roughage) 4 – 5 kg of grain mixture (concentrated) and 27 – 32 litres of water. Besides that minerals and vitamins are also required., Grooming: Cattle needs to be brushed regularly , massaged and cleaned., Health care: A veterinary doctor must visit frequently the farm for vaccination. Sick animals needs to be isolated till their recovery., Sanitation: A good sanitation measures should be adopted with the farm., Common problems of adolescence, Adolescence is the period from the onset of puberty upto the completion of growth and maturity (12-20 years). It is the most sensitive period in which feeling of independence is flowing throughout the blood of an adolescent. Therefore experimentation for looking and feeling is quite common. So it leads to drug abuse, alcoholism and tobacco addiction., Drug: A drug is that chemical which is usually taken for the treatment of some diseases on the advice of the some doctor, physician and is withdrawn as soon as the desired effect is achieved. The constant use of certain drugs forms a habit and one becomes a drug dependent. It is called drug dependency or drug addiction., Types of drugs: There are a no. of drugs on which people become dependent. On the basis of the mode of action on brain, drugs are of four types: sedative and tranquillizers, opiate narcotics, stimulants and hallucinogens., Sedatives and tranquillizers: These drugs act as depressants and depress the activities of the central nervous system. They give them a feeling of calmness, relaxation or drowsiness in the body. Their high doses may induce sleep. Tranquillizers lower tension and anxiety without inducing sleep. Examples are barbiturates and benzodiazepines e,g valium etc., Opiate narcotics: These act as depressants (suppress activity of brain) and analgesic (relief from pain). So are commonly called pain killers. The opiate narcotics are used for cough relief and for the treatment of vomiting and diarrhoea. The opiate narcotics are briefly called opiates which includes opium and its derivatives., General effect: opiates relieve pain , reduce tension and anxiety, lower blood pressure and breathing rate, undue drowsiness , constrict the pupil and reduce visual activity. An overdose stop respiration and cause death. If the drug are not available to the addict he shows terrible withdrawal symptoms like rhinorrhoea (excess nasal discharges), lacrimation (excess secetion of tears) , vomiting , diarrhoea, shivering , muscle twitching , epilepsy etc. the opiate dependent losses weight as well as interest in work and fertility., Opium: It is called AFIM in northern India. Opium in the air dried milky latex which is obtained by meshing the unripe capsule (fruit) of white poppy plant (papaver somniferum). It has a reddish brown colour , heavy smell and a bitter taste. Its derivative are morphine, codeine and heroin., Morphine and codeine: These are the derivatives of opium. Morphine is a most valuable analgesic but it causes addiction. Codein is a mild analgesic but causes no addiction , so it is commonly used in cough syrups., Heroin: (diacetylmorphine or diamorphine), Heroin is formed from morphine by acetylation. It is highly addictive and treated as a dangerous opiate so banned for medical use. It is taken orally or inhaled or injected. As the heroin addicts are careless about the needles and syringes so can cause blood poisoning , hepatitis and AIDS., Smack: It is crude by product of heroin synthesis and is commonly called brown sugar. As it is cheaper than heroin so considered as poor man’s heroin., Stimulants: These drugs temporarily stimulate the nervous system, make a person more alert, wakeful active and cause excitement. The stimulants include caffeine, cocaine and amphet amines., Caffeine: It is an alkaloid derived from the leaves of tea plant (thea chinensis), seeds of coffee plant (coffee arabia) and seeds of coca plant ( Theobroma cacao). Caffeine is a mild stimulant and is taken as beverages – tea, coffee, coca and cola drinks. It increases alertness and thought and is used as a cardiac stimulants. Its excessive use causes addiction., Cocaine: It is derived from the leaves and young branch of south American plant, Erythroxylon coca. Cocaine is used as local anesthetic and stiumulant. Its bad effects are lack of sleep, loss of appetite and hallucination. Its overdose may cause severe headache, convulsions or death due to cardio-vascular or respiratory failure., Amphetamines: These are synthetic drugs which are commonly called pep pills or antisleep drugs. They are strong stimulants which are used by truck drivers , students and night workers who want to keep awake themselves during the night. But they do not remove fatigue. However they impair vision and judgement of distance., Hallucinogens: These are those drugs which change thoughts , feelings and perceptions of an individual who claims that he can see sounds and hear colour. These drugs are also called psychedelic drugs because they have a strong effect on the cerebrum and sense organs. They include chemicals such as LSD ( lysergic acid diethyl amide) and products of hemp plant., LSD (Lysergic acid diethylamide): It is derived from the dried fruiting body (sclerotium) of the ergot fungus ( a pathogen of rye grass). It is most powerful hallucinogen which causes horrible dreams floating sensation and severe damage to CNS. It also brings about chromosomal and foetal abnormalities., Products of hemp plant ( cannabis sativa, c. indica), Bhang: It is derived from leaves and flowering shoots., Ganja: It is derived from unfertilized female inflorescence., Charas: Derived from dried flowering plants., Marijuana: Derived from dried flowering plants., When these drugs are consumed immediately after that one feels dilation of the pupil of eye, blood sugar level rises and frequency of urination increases. They are often mixed with tobacco and smoked., Effects of drug addiction on family , society and addicts, The drug addicts not only suffer from themselves from its ill effects but also bring miseries for the family and for the society., Effects of family: the drug addicts create problems for their families. They neglect duty and lose job. This may deprive the family from the basic needs. The children feel frustrated and insecure and couldn’t get better education. The ties between wife and husband worsen and in certain cases ends with divorce., Effect on society: the addicts get the supply of drugs from illegal sources so they encourage smuggling and other illegal activities resulting in social problems., Effect on individual: it is evident that the drugs affect the central nervous system and their prolonged use causes permanent damage to it. The body fails to work without drugs ultimately other organs also get involved and damaged and the addict become victims of other various other diseases., Alcohol: Regular consumption of alcohol either in low concentration (beer, wine etc) or in high concentration (brandy, whisky , rum etc) causes dependency on alcohol is called alcoholism and the person who consumes or drink it regularly and has become a habitual is called an alcoholic., Why people take to drinking: Research had proved that people who resort to drinking offer one or more of the following reasons., Social pressure, desire for excitement, liking of taste, desire to escape from disappointments and failures, desire to overcome the hardships of daily life, family’s history., When a person drinks alcohol it passes to the stomach and a small amount is also carried to small intestine. It is quickly absorbed in the stomach and in upper part of small intestines. Then within minutes it reaches to all the cells and tissues of the body and at once starts its oxidation and a large amount of heat is produced as this heat is not needed to the body. It is taken up by the blood and is carried to the skin for dissipation. This gives a false impression of warmth in the body. The blood supply is greatly reduced to the internal organs resulting in fall of temperature. Many people think that alcohol is a stimulant. But actually it is not a stimulant but acts as a sedative (less functional activity), analgesic (relieves pain) and anesthetic ( causes loss of sensation)., Effects of alcohol: Alcohol affects not only the individual but also his family and the society as a whole., Effects on individual health: Alcohol reaches all body organs. So all of then are affected. However certain organs are affected more than other., Effects on nervous system: Alcohol has an anaesthetic effect on the nervous system. It acts on all neurons and effects may functions such as orientation , alertness, coordination , judgement and memory. It first effects on cerebrum followed by cerebellum and other parts. Thus a person loses judgement , will power and self control. Anxiety disappears and the person feels gay and light headed. Which is shown by foolish laughter or sadness and weep. Moral sense is lost, leading to antisocial behaviour., Effects on stomach: A large dose or high concentration of alcohol causes increased secretion of gastric juices which causes inflammation of gastric mucosa leading gastritis., Effects on liver: The most important organ which is damaged by alcohol is the liver. Inside the liver the alcohol is changed into more toxic compound – acetyl aldehyde which provides energy to synthesize fats from alcohol. So liver becomes the store house of fats which leads to fatty acid syndrome. Liver becomes hard and dry and liver cells are replaced by fibrious tissues. This is called cirrhosis. Once the liver is damaged it affects the other organs of the body also., Effects on heart: Alcohol stimulated the deposition of alcoholic fats on the walls of the blood vessels which become rigid and brittle. This increases blood pressure and adversely affects the working of the heart., Effects on kidney: kidneys are over worked in eliminating the excess water often taken with alcohol. Alcohol also decreases glucose level in the blood., Unit IV, Biotechnology and its Applications, Biotechnology:, Biotechnology deals with techniques using live organisms to produce useful materials for mankind or for human needs. It is the technological exploitation of biological process including genetic engineering in order to obtain useful material for agriculture , industry , domestic medical and other uses., Age old techniques like preparations of curd, bread or wine which are all medicated by micro organisms is also a form of biotechnology. However today it is excluded from biotechnology or brought under the category of old biotechnology., Modern biotechnology is the use of genetically modified organisms (GMOs) or genetically engineered plant and animal cells which not only to enhance their productivity but also give rise to a new product on large scale. It has several branches like medical biotechnology e,g developing new DNA vaccines, synthesizing new genes, in – vitro fertilization leading to test tube babies , crop biotechnology , microbial biotechnology, tissue culture etc., The European federation of biotechnology ( EFB) has defined biotechnology integrated both the traditional view and modern molecular biotechnology., “ the integration of natural science and organisms, cells, parts or there and molecular analogue for products and services., ., Recombinant DNA technology, Recombinant DNA technology includes techniques of cutting DNA into specific fragments by using restriction endonuclease and joining these fragments with the help of enzyme ligase. These fragments of foreign DNA inserted into a vector which may be plasmid or viruses., Tools of recombinant DNA technology, Genetic engineering or recombinant DNA technology requires the following key tools : restriction enzyme, polymerase enzymes, ligase, vectors and the host organism., Restriction enzyme: Steward linn and Werner Arber (1963) isolated the two enzymes which were responsible for restricting the growth of bacteriophage ( virus that infects the bacteria) in E.coli. among these two one added methyl group to DNA, while other cut DNA. The enzyme that cuts DNA is known as Restriction endonuclease. the enzyme can cut DNA at a particular points having specific sequence of six base pairs. Upto now 900 such restriction enzymes have been isolated from over 230 strains of bacteria., While naming of enzymes the first letter of the name comes from the species of the prokaryotic cell from which they were isolated e,g ECO I comes from Escherichia coli and, Restriction enzymes belong to a larger class of enzymes called as nucleases. They are of two types:, Exonuclease: They remove the nucleotides from the ends of DNA., Endonucleases: They cut DNA molecule from inside., Restriction endonucleases cut DNA at specific sites called as recognition sequences. Once it finds its specific recognition sequence it will bind to the DNA and cut each of the two strands of the double helix at specific points in their sugar phosphate backbone. The recognition sequence of each restriction endonuclease is a palindromic region, the two strands of DNA possess the same base sequence but in opposition fashion 5’ – 3’ and 3’ – 5’ direction. It is similar to palindromic wards which reads the same in both directions e,g RAMAR,, MALYALAM, MADAM., 5’…….GAATTC……..3’, 3’…….CTTAAG………5’, Restriction endonuclease cut the strand of DNA a little away from the centre of the palindromic sites but between the same two bases on the opposite strands. This leaves stranded portions at the ends. Each strand now contains overhanging stretches called sticky ends. They are named so because they form Hydrogen bonds with their complementary counterparts I,e opposite strand. These sticky ends facilitate the action of the enzyme DNA ligase. Restriction endonuclease are used in genetic engineering to form Recombinant molecules of DNA., Separation and isolation of DNA fragments, The cutting of DNA by restriction endonuclease results in the formation of various fragments of DNA. These fragments can be separated by a technique known as Gel electrophoresis. This is a technique in which biomolecules are separated under an electric field when placed over a matrix of gel cathode ( -) and anode (+) are present at the two ends of the instrument. The matrix is generally made of agarose. The electric field is activated. DNA fragments are negatively charged. They move towards the positively charged anode. Agarose has a sieving effect, DNA fragments separate according to their size. Larger fragments move slowly while the smaller fragments move fast and reach the farther end., As the DNA fragments cannot be seen in the visible light and without staining. Now they are stained with ethidium bromide and exposed to ultra – violet radiations. They appear as bright as orange colour bands. The bands are cut out of agarose gel and extracted. This extraction step is called elution (removal of adsorbent). The DNA fragments purified in this way are used in constructing recombinant DNA by joining them with coloning vectors., Coloning vectors, They are vehicles or carriers of desired DNA fragments ( passenger DNA). They have the ability of independent replication and hence can increase the copies of desired genes e,g plasmids and bacteriophages. Number of plasmids is variable in bacterial cells. Some cells may have 15 – 100 or higher. But their common no. is 1 – 2. Similarly a no. of bacteriophages mature in a bacterium. Therefore if we are able to recombine a piece of DNA (passenger DNA) with bacteriophage genome or plasmid and then introduce it in a plasmid free bacterium. The vector would multiply equal to no. of plasmids or bacteriophages that normally develop in it. Following features are required for cloning vector:, Origin of replication: It is a DNA sequence from which replication starts. Any piece of DNA when linked to this sequence can replicate with in the host cell. The sequence also possesses nearby replication control which determines the no. of copies it would form. Therefore , the selected plasmid should have an origin of replication that supports high copy number., Selectable markers: The vector requires a selectable marker, which helps in distinguishing a recombinant from non – recombinant DNA. It also helps in eliminating the non transformed bacterial cell from transformed bacterial cells. Transformation means the passage of foreign DNA or plasmid containing the passenger DNA into a host cell., Plasmids has a selectable marker. Normally genes encoding for antibiotics resistance e,g ampicillin, chloramphenicol, tetracycline are considered useful as selectable marker for E.coli PBR – 322 has two resistance genes ampicillin and tetracycline resistance while PUC – 18 has only ampicillin resistance gene., Cloning sites or recognition sites: In order to link the alien DNA the vector to have very few preferably single recognition sites for the commonly used restriction enzymes. Presence of more than one recognition site will cause DNA fragmentation and disturb the gene cloning process. In PBR 322 alien DNA is ligated generally In the area of BamH1 site of tetracycline resistance. The plasmids are passed into bacteria during transformation. The non recombinant plasmids can grow well in both ampicillin and tetracycline medium, while as the recombinant can grow only in ampicillin containing medium but will die out in tetracycline containing medium. Inactivation of gene due to insertion of alien DNA is called insertional inactivation., s, Process of recombinant DNA technology, Recombinant DNA technology or genetic engineering is technically a hi – tech process which involves several steps in specific sequence. Such as , isolation of DNA, fragmentation of DNA by restriction endonucleases, isolation of desired DNA fragments, ligation of DNA fragments into vector. Trasnsfer of DNA into host cells, culturing of host cells in a bioreactor and extraction of desired product., Isolation of genetic material or DNA: Genetic material is contained inside the cells. In order to obtain DNA in purest form even without attached histones and other proteins. The cultured cells from which the desired genes or DNA segments are to be obtained are separated. These cells are treated with lysozyme, in case of bacteria cellulose and pectinase (plant cells) and chitinase for fungal cells. After treatment these cells are homogenized and centrifuged in order to rupture the cells as well as nuclear envelope. The homogenized products of the cells are treated with proteases for digestion of proteins , ribonucleases for digestion of RNAs , amylase and lipases. DNA remains intact. It is precipitated by the addition of chilled ethyl alcohol. DNA appears as a mass of very fine threads., Cutting of DNA at specific locations and its pasting: The purified DNA molecule are subjected to restriction enzymes at the optimal conditions for that specific enzymes. Agarose gel electrophoresis is employed to check restriction enzyme digestion. As DNA is negatively charged, the cut segment move faster towards the +ve electrode or anode. The desired gene are identified and separated. The genetic material which is used for transfer to other organisms is called passenger DNA., Formation of recombinant DNA: Both the passenger and vehicle DNA are treated separately with the same restriction endonuclease. it produces complementary sticky ends. Alkaline sulphate is used to check the self ligation. The two types of DNAs (passenger and vehicle) are now joined together with the help of DNA ligase. However, it is necessary that the vehicle DNA or vector DNA should receive only one passenger DNA. The union of plasmid (vehicle DNA) and the desired passenger DNA fragment produces recombinant or rDNA ., Amplication of gene of interest using PCR: PCR or polymerase chain reaction. In this reaction multiple copies of the gene or (DNA) of interest is synthesized in vitro using the two sets of primers (small chemically synthesized oligonucleotides that are complementary to the regions of DNA) and the enzyme DNA polymerase. There are three steps in PCR I,e denaturation , annealing and extension., Denaturation: The isolated target DNA is heated to a high temperature of about 940c. it leads to the separation of two DNA strands which are now ready to act as templates., Annealing: The oligonucleotides primers anneal or hybridize to each of the single stranded DNA template at its 3’- end. This step is performed at lower temperature., Extension: Now deoxynucleotide triphosphates Mg+ and tag polymerase are added. The temperature required for this step is 720c. polymerase synthesis the DNA strands complementary to template strand. This process is called extension. If the process of replication of DNA is repeated many times the segment of DNA can be amplified to approximately billion times I,e billion copies are made. The DNA segment can be used to ligate with the vector for formation of rDNA and its coloning., Insertion of r DNA into host cell/ organism: There are several methods of introducing the ligated DNA into recipient cells. Now if the r DNA contains a gene for resistance to an antibiotic ( e,g ampicillin) is transferred to E. coli cells. The E. coli become transformed into ampicillin resistant cells. If these transformed cells are spread in agar plates which contains ampicillin. They will grow and survive. While as the untransformed or normal cells will die. Since due to ampicillin resistance gene, one is able to select a transformed cell in the process of ampicillin. The ampicillin. The ampicillin resistance gene in this case is called a selectable marker., Obtaining the foreign gene product: when we insert a piece of alien DNA (passenger DNA) into a cloning vector and transfer it into a bacterial , plant or animal cells. This alien DNA gets multiplied. In almost all recombinant techniques, the ultimate aim is to produce a desirable protein or biochemical which is useful to humans., After having cloned the gene of interest in order to induce the expression of the desired and target protein one has to consider producing it on a larger scale. The container in which the biochemical process is carried out by using living cells and their growth medium is called bioreactor or fermenter. It can use either batch culture of continuous culture systems. During the batch culture system the transformed recombinant cells are allowed to grow in al large bioreactor till the maximum biochemical is formed. This biochemical is collected , the bioreactor is amplified, cleaned and again filled with the cells and culture medium. In continuous culture system , there is a regular drainage of medium and culture from one side and addition of fresh medium from the other side. During this system a large quantity of biomass and the desired products are formed., Down – stream processing: it is the recovery of products from the full grown genetically modified cells. Its modification and preservation is carried out when the sampling report indicates the completion of biosynthetic process and from and presence of product in the cells. The separated product is purified and subjected with suitable preservatives. Then it undergoes through the clinical trails in order to know its use and any immediate or long term adverse effect. Then each and every batch of the product has to pass through strict quality control test., Application of r DNA technology, Study of molecular events: this technology is used in study of molecular events of various developmental stages like cellular differentiation , ageing etc., Gene maps: it is used to prepare the gene maps of different individuals., Nitrogen fixation: genes which codes for fixation of nitrogen can be made a part of genome of all plants., Study of defective genes: it is used to study defective genes., Recombinant products: the r DNA technology gifted us a number of biochemicals In the form of drugs, vaccines and antibiotics., Foods with extra biomolecules., Biotechnology and its application in heal, Biotechnology or DNA technology have made a good impact in the area of healthcare of mass production of safe , newer and more efficient therapeutic drugs also known as recombinant drugs. These drugs do not induce unwanted immunological responses as is common in case of drugs which are derived from non human sources. At present about 30 recombinant therapeutic drugs have been approved for human use. In India 12 of them are marketed., Genetically Engineered Insulin, Insulin is a pancreatic hormone which is essential for the maintenance of glucose – glycogen balance in the body. When its deficiency occurs, the glucose content of blood rises because cells are unable to take up the glucose from the blood and change it into glycogen. It results in a diseases called diabetes mellitus. This diseases is controlled by injecting the small doses of insulin in the form of injections. This insulin was earlier extracted from the pancreas of slaughtered cattle’s and pigs. Although this insulin are similar to human insulin, their composition is slightly different . consequently , a no. of patients immune systems produce antibodies against it neutralizing the actions and resulting in inflammatory response at the sites of infection., Therefore efforts were made to synthesize human insulin through recombinant DNA – technology. Insulin consists of two polypeptide chains, chain A and chain B. these are linked together by disulphide bridges. In humans insulin is synthesized as a pro – hormone ( like proenzyme, pro hormone needs to be processed before it becomes a fully mature and functional hormone., This prohormone contains an extra stretch called the c – peptide. This c – peptide is not present in mature insulin and is removed before mutation., During the r DNA technology the earliest method is to take out insulin gene from healthy human leucocytes and use it in preparation of r DNA., Two DNA strands sequences were prepared by Elilly for the two chains A (for 21 amino acids) and B (for 30 amino acids) of insulin by reverse transcription of their mRNA., Plasmids of E. coli (e,g puc – 18) and insulin gene were treated with the same restriction endonuclease. it produced sticky ends in both. The two are joined together by DNA ligase. It produces r DNA in the form of plasmids carrying the insulin genes. The insulin genes are attached in the vector plasmids adjacent to Z – gene encoding B – galactosidase. A plasmid free E.coli is inoculated with recombinant plasmids in the presence of calcium chloride or other chemicals which increases the ability of bacterial cells in obtaining plasmids from outside., The genetically engineered bacteria are tested for the formation of fusion polypeptide consisting of insulin sub – unit and galactosidase sequence. As the presence of both insulin sub – unit and B – galactosidase sequence. As the presence of both insulin subunits is ensured. The bacteria are first multiplied or cloned. They are then introduced in a fertilized bioreactor having the growth medium. The bacteria are harvested and insulin is extracted after extraction. It is purified , by treating the fusion of polypeptide with bromide which separates B – galactosidase polypeptide and purifies the insulin sub units. This extracted insulin is similar to human insulin so it is called Humulin., Gene Therapy, It is a therapeutic treatment to replace a faulty gene by a normal healthy and functional gene. Gene therapy is a collection of methods that allows the correction of a gene defect that has been diagnosed in a child/embryo. In gene therapy or embryo to take over the function in order to compensate the non functional or faulty gene., The first clinically gene therapy was given in 1990 to a four year old girl with adenosine deaminase (ADA) deficiency. It is a crucial enzyme for the functioning of immune system. This disorder occurs due to the deletion of the gene for adenosine deaminase. It can be cured in children by two methods: bone marrow transplantation and enzyme replacement therapy. However by these methods the disease is not cured completely., Lymphocyte is a kind of white blood cells are extracted from bone marrow of the patient and cultured outside. A good copy of human gene is encoding this enzyme, functional ADA is introduced into these cells using a retroviral vector. They are re – injected into the patient., As these cells are not immortal, therefore the patient requires periodic infusion of such genetically engineered lymphocytes. However if the gene isolate from marrow cells producing ADA is introduced into cells at early embryonic stages, it could be permanent cure., Be like diamond which is found rare , not like a stone which Is found everywhere.