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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , CHAPTER NO: 6, , BIOMOLECULES, o Biochemistry: branch of biology which deals with study of chemistry, of all living organisms ., o Biochemistry deals with study of change in molecular basis of plants,, animals and micro-organisms., o Biochemistry helps to understand all biological processes and, communication within and between cells as well as chemical basis of, inheritance., o Chemical analysis of living organisms indicates presence of most, common elements i.e. Carbon, hydrogen, nitrogen , oxygen, sulphur,, calcium, phosphorous , magnesium along with iron, selenium, zinc,, iodine ., o Biomolecules are polymers of simple subunits/ monomers of organic, and inorganic substances., o Biomolecules are of two types: Organic and Inorganic ., , o, , Organic biomolecules are macromolecules [large molecular weight ], and micromolecules[Small molecular weight] ., o Polysaccharides, polypeptides and polynucleotide’s are, macromolecules where as lipids and secondary metabolites are, micromolecules., o Inorganic biomolecules consist of prime elements , macro elements [, macro minerals] and trace elements [ micro minerals], o Biomolecules are considered as structural units of cell., 1, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o The different components of cell contain polymers of carbohydrates,, proteins, nucleic acid and fats., 1. Carbohydrates: Polysaccharides are polymers of monosaccharides, [simple sugar molecules]., 2. Proteins: Polypeptides are polymers of amino acids/ peptides., 3. Fats/ lipids: Triglycerides are polymers of fatty acids and glycerol., 4. Nucleic acids: Polynucleotide's are polymers of nucleotides., , 1., , Carbohydrates :, , o Definition: The organic compounds produced in the chlorophyll, containing cells during photosynthesis., o Chemical component: Carbon ,Hydrogen and Oxygen, o Functional Groups:, 1] Aldehyde (- CHO) or Ketone(C=O) 2] Hydroxyl (- OH), o Special arrangement of functional groups: CHO molecule, characterized by presence of either aldehyde or ketone group or two or, more hydroxyl groups., o H & O ratio: 2: 1, o Calorific value: 1gram CHO = 4 Kcal energy, o General Formula:, 1] Simple sugar : CnH2nOn or (CH2O)n, 2] Complex sugar : ( C6H10O5 )n, o Significance: Simple sugar molecules participate in metabolic, reactions and complex sugar forms storage and structural units., , CLASSIFICATION OF CARBOHYDRATES: : [On the basis of number, of sugar units] :, a. Monosaccharides b. Disaccharides, , a. Monosaccharide:, , c. Polysaccharides, , o Simple sugar molecules having 3 to 7 carbon atoms called as, monosaccharide., o Monosaccharides are crystalline, soluble and sweet in taste., o Monosaccharide is basic units of complex carbohydrates.[structural, units]., o Monosaccharides are building blocks or monomers of complex, carbohydrates [polysaccharide]., o They cannot be further hydrolysed into smaller molecules., , ,, 2, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , XI SCIENCE, , LECTURE NOTES BIOLOGY, , o Classification:, 1. On the basis of number of carbon atoms:, Types, 1. Triose, , Number of carbon atoms, 3 carbons, , Examples, Glyceraldehydes, , 2. Tetrose, , 4 carbons, , Erythrose, , 3. Pentose, , 5 carbons, , Ribose Deoxyribose, , 4. Hexose, , 6 carbons, , 5. Heptose, , 7 carbons, , Glucose ,Galactose,, Fructose, Sedoheptulose, , a. Glucose: It is most important fuel in living cells. The small size, and solubility in water allows glucose to pass through the plasma, membrane of cell. During cellular respiration, glucose oxidized to, form Energy in the form of ATP. The concentration of glucose is 90, mg /100 ml of blood, b. Galactose: Galactose is isomer of glucose and present in alpha, and beta form. Galactose combines with glucose to form lactose., Galactose cannot play same role in respiration as glucose., c. Fructose: It is hexokinase sugar present in fruit and five atom, ring structure. Fructose combines with glucose to form sucrose., 2. On the basis of functional group:, Type, , Description, , Example, , 1. Ketose sugar/, Ketoses :, , Monosaccharide which contain, ketone as a functional group, , Fructose ,, Ribulose, , 2. Aldose sugar /, Aldoses :, , Monosaccharide which contains, aldehyde as a functional group, , Glucose ,, Xylose, , b. Disaccharides :, o, , Carbohydrates made up of two monosaccharide units called as, disaccharides., o Disaccharides are soluble in water, crystalline and sweet in taste., o The covalent bond that joins monosaccharide units are glycosidic, bonds., o During condensation, one water molecule released during hydrolysis, i.e. conversion of disaccharide into monosaccharide., , 3, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o Examples :, 1. Sucrose : Glucose + Fructose, It is non reducing sugar because it lacks free aldehyde or ketone, group., 2. Lactose : Glucose + Galactose, It is reducing sugar present in milk only. Lactose is present in, beta form. Lactose made up of beta glucose and beta galactose., 3. Maltose : Glucose + Glucose, Maltose is reducing sugar present in cereals. Maltose present in, the form of starch., , C. Polysaccharides:, , o Carbohydrates made up of many monosaccharide units or, monosaccharides undergoes a series of condensation reactions, [polymerization] and forms large complex molecule c/a, polysaccharides., o Polysaccharides are amorphous, insoluble and tasteless., o General formula of polysaccharide is ( C6H10O5 )n n= no. of poly., Units., o Classification :, 1. Homopolysaccharide: Polysaccharides made up of only one type of, monosaccharides called as Homopolysaccharide., Example: Cellulose, Starch, Glycogen, Pectin, Lignin, 1. Starch: Starch stored in plant. It exists in amylase and, amylopectin forms and both formed from alpha glucose., a. Amylase : unbranched polymer forms helical structure and, forms colloidal suspension in hot water., b. Amylopectin: branched polymer and completely insoluble in, water., , 4, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , 2. Glycogen: It is stored in animal body [Liver and muscles] and, hydrolysed as per need of body. It is amylopectin with very, short distance between the branching side-chains., 3. Cellulose: It is straight polymer of beta glucose. Cell wall of, plant cell made up of cellulose. The arrangement of glucose, units in polymer chain and hydrogen bonding between, neighboring chains makes it tough, 2. Heteropolysaccharides: Polysaccharides made up of different types, of monosaccharides called as heteropolysaccharides., Example: Hyaluronic acid [joining of follicular cells of corona radiata of, female gamete egg/ovum] , Heparin [anticoagulant of blood],Chitin, , , , Biological significance:, , 1. Readily source of energy: CHO is readily source of energy., 2. Acts as principal respiratory substrate: Glucose is main substrate, used for synthesis of ATP [Adenosine triphosphate] due to availability., 3. Synthesis of ATP molecules: Glucose undergoes oxidation to form, ATP molecules .ATP is energy currency of cell., 4. Acts as structural components : Polysaccharides serves/acts as, structural component of cell wall i.e. peptidoglycan in monera ,, cellulose in protista , true cellulose in plants and chitin in fungi, 5. Serve as reserve food material : Polysaccharides serves as reserve, food material i.e. starch and glycogen, 6. Maintenance of body temperature: Energy released from glucose in, the form of ATP used to maintain body temperature., 7. Regulation of metabolic reactions: Energy released from glucose in, the form of ATP used for anabolic reactions., 8. Oxidation of fat and proteins: Carbohydrates helps in oxidation., , 2. Lipids :, , o Definition: Group of organic components having oily or greasy, consistency with long hydrocarbon chain containing H,C and O called, as lipids., o Nature: Lipids are insoluble in water but freely soluble in organic/, non polar solvents (benzene, chloroform and ether), o Chemical composition:, 1. Simple lipids: C ,H and O atoms but H: O ratio is less than 2:1, 2. Compound lipids: C, H ,O + N, S, & P., o Monomers: Fats are monomers of fatty acids and glycerol, a. Fatty acids : long straight chain of hydrocarbon with carboxyl group (COOH)., 5, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , a] Saturated Fatty acids : b]Unsaturated Fatty acids :, , Saturated fatty acids, , Unsaturated fatty acids, , Fatty acids without double bonds, between carbon atoms of its chain, called as saturated fatty acids, , Fatty acids with one or more, double bonds between carbon, atoms of its chain called as, unsaturated fatty acids, , Consist of maximum possible, hydrogen atoms, , Consist of minimum possible, hydrogen atoms, , Solid at room temperature, , Liquid at room temperature, , Animal fat[semisolid] and butter, [solid] are sources of saturated, fatty acid, Example: Palmitic acid and, Stearic acid, , Plant fat is source of unsaturated, fatty acid, Example: Linolenic acid, Linoleic, acid , Archidonic acid and Oleic, acid, , b. Glycerol : 3 Carbon alcohol with 3 hydroxyl group (-OH), o, Functional groups: Carboxyl group at fatty acid molecule and, hydroxyl group at glycerol., , , , Classification of lipid:, , 1] Simple Lipids, , 2] Compound lipids, , 3] Derived lipids, , 1. Simple Lipids :, o Simple lipids are esters of fatty acids with various alcohols., A. Fats :, o Fats are esters of fatty acids with glycerol [ CH2OH-CHOH-CH2OH ]., o Fats are classified as, a. Monoglycerides: Simple lipid which contains only one fatty acid, molecule attached to glycerol., b. Diglycerides: Simple lipid which contains two fatty acid molecule, attached to glycerol, c. Triglycerides/ Neutral fat: Simple lipid which contains many fatty, acid molecules attached to glycerol., Unsaturated fats are liquid at room temperature c/a oils., Unsaturated fatty acids are hydrogenated to produce fat. [vanaspati, ghee], 6, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o Significance :, 1. High Calorific value: Fats are rich source of energy., 2. Acts as reserve food material :, a. Seed of plants: nutritious tissue endosperm., b. In animals : Adipocytes of adipose tissue, 3. Heat insulator : fat deposited in subcutaneous tissue acts as heat, insulator and minimizes loss of body heat., 4. Acts as cushions : Fat deposited around internal organs acts as, cushion to absorb mechanical shocks., B. Wax:, o Waxes are esters of long chain fatty acids with long chain alcohols, (except glycerol) and ketone., o They are most abundant in the blood, the gonads and the sebaceous, glands., o Waxes are solid at ordinary temperature., o Waxes are not as readily hydrolysed as fats., o It forms water insoluble coating on hair and skin in animals as well as, forms coating on stems, leaves and fruits., , 2. Compound lipids:, o Lipids contain additional elements (nitrogen, phosphorous, sulphur, and protein) in addition to fatty acid and glycerol called as compound, lipids., o Compound lipids are esters of fatty acids containing other groups like, phosphate, sugar etc., o Compound lipid contains a molecule of glycerol, two molecules of fatty, acids and a phosphate group or simple sugar., o Example : a. Phospholipids b.Glycero-phospholipids c. Glycolipids, 7, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , a. Phospholipids: It have a nitrogenous compound attached to the, phosphate group. Phospholipids have both hydrophilic polar, groups [phosphate & nitrogenous group] and hydrophobic nonpolar groups [hydrocarbon chains of fatty acids. Phospholipids are, structural units of plasma membrane., b. Glycero-phospholipids : Each glycero phospholipid molecule, consists of a small polar head group and two long hydrophobic, chains, c. Glycolipids: It contains glycerol, fatty acids and simple sugar, [galactose] and nitrogen base. Also known as cerebrosides., Cerebrosides found in white matter of brain and myelin sheath of, nerve., , 2. Derived Lipids :, o The hydrolytic products of lipids are called as derived lipids., Derived lipids are as follows, a. Sterols/Steroids: Steroids contains carbon atoms arranged in four, interlocking rings. It composed of fused hydrocarbon side chain, • Cholesterol is common sterol present in all cells of the animal body, especially in nervous tissue. Cholesterol exists either free or as, cholesterol ester. Cholesterol absent in plant cell., , Adrenocorticoids, sex hormones Progesterone,, Testosterone and vitamin D are synthesized from cholesterol., , 8, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , Phytosterol is sterol present in plants., Diosgenin is phytosterol present in, Dioscorea/yam plant which is used in, the manufacturing of antifertility pills, i.e. birth control pills., b. Carotenoids: Carotenoids are two, six carbon rings with highly, unsaturated chain of hydrocarbons., Carotenoids present in thylakoids of chloroplast and, Chromoplast in higher plants, Example: α-carotene, β- carotene and Xanthophylls, , , , Biological Significance :, , 1. Acts as high energy reserve food material: Fat is rich source of, energy., 2. Acts as structural units: Phospholipids is structural unit of plasma, membrane in eukaryotes., 3. Acts as component of enzyme system: Lipids acts as component of, enzyme system., 4. Synthesis of Vitamin D: Cholesterol helps in synthesis of Vitamin D., 5. Precursor of sex hormone: Cholesterol is precursor of sex hormones, 6. Synthesis of amino acids: Fatty acids help in synthesis of amino, acids., 7. Carrier of fat soluble vitamins: Fats acts as carriers of fat soluble, vitamins, 8. Absorption of nutrients: Phospholipids helps in absorption of, nutrients., 9. Acts as heat insulator: Subcutaneous fat present in animals acts as, heat insulator., 10. Proper metabolism of sugar: Fats helps in proper metabolism of, sugar., 11. Provides water proof medium : Wax provides water proof medium, 12. Checks rate of transpiration in plants: Wax helps in minimizing, rate of transpiration in plants., 13. Constituents of bile: Cholic acid (Steroid) is a constituent of bile., Bile helps in digestion, , 3. Proteins :, , o Definition: Proteins are highly complex nitrogenous compounds made, up of amino acids or Proteins are long chain polymers of amino acids., o Nature: proteins are large macromolecules with high molecular weight., 9, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o Chemical composition: Carbon, hydrogen and oxygen along with, nitrogen .Sulphur is also present., o Component of cell: Protein is most abundant organic component of, the cell also host specific., o Specialty : Proteins shows slight variations in structure and numbers, ([Bacterial cell: 2000 and Human cell: 1, 00,000], o Amino acids: Amino acids are structural and functional units of, proteins. Amino acids are essential as well as non essential. The, amino acids are as, o Functional groups: 1. Amino group (-NH2), 2. Carboxyl group (- COOH), , o Terminals:, a. N -terminal :Long chain of amino acid contain free amino, acid group at one end called as N-terminal, b. C- terminal : Long chain of amino acid contains carboxyl group at, another end called as C-terminal, o Peptide linkage: Amino group of one amino acid linked to carboxyl, group of other amino acid by peptide linkage. Two amino acids, condensed by removal of a water molecule i.e. OH from COOH and H, from NH2, , Amino acid residue /Peptide: The remainder of each amino acid, after removal of water molecule is called as residue., o, Disulphide bonds (-s-s-) : The additional bonds which maintains, folding structure of polypeptide chain is called as disulphide bonds., , o, , 10, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o Characteristics of Protein :, , o Proteins are large molecules containing amino acid units ranging from, 100to 3000. Proteins have high molecular weights., o In proteins, amino acids are linked together by peptide bonds which, join the carboxyl group of one amino acid residue to the amino group of, another residue., o A protein molecule consists of one or more polypeptide chains., o Proteins can contain any or all of the 20 naturally occurring amino acid, o Primary structure: The linear sequence of amino acids in polypeptide, chain of a protein forms its primary structure., o Spiral Helix: Functional proteins have3-dimensional conformation, Some proteins such as keratin of hair consists of polypeptide chain, arranged like a spiral helix. Such spirals are in some cases right, handed called -helix, in others left-handed called β-helix., o Secondary structure: The spiral configuration is held together by, hydrogen bonds. The sequence of amino acids in the polypeptide chain, also determines the location of its bend or fold and the position of, formation of hydrogen bonds between different portions of the chain or, between different chains. Due to formation of hydrogen bonds peptide, chains assume a secondary structure., o Pleated Sheet: In some proteins, two or more peptide chains are linked, together by intermolecular hydrogen bonds. Such structures are called, pleated sheet. Pleated sheet structure is found in protein of silk fibres, o Tertiary structure: In large proteins such as myoglobin and enzymes,, peptide chains are much looped, twisted and folded back on themselves, due to formation of disulphide bonds. Such loops and bends give the, protein a tertiary structure., o Quaternary structure: Whereas in haemoglobin, protein subunits are, held together to form quaternary structure., o Proteins are extremely reactive and highly specific in behavior., o Amphoteric Nature: Proteins are Amphoteric in nature i.e. they act as, both acids and bases. The behavior of proteins is strongly influenced by, pH. Like amino acids, proteins are dipolar ions at the isoelectric point, i.e. the sum of the positive charges are equal to the sum of the negative, charges and the net charge is zero., o The ionic groups of a protein are contributed by the side chains of the, polyvalent amino acids., o Basic proteins: A protein consists of more basic amino acids such as, lysine and arginine exists as a cation and behaves as a base at the, physiological pH of 7.4. Such proteins are called basic proteins., Histone of nucleoproteins is basic proteins., o Acidic proteins: A protein rich in acidic amino acids exists as an anion, and behaves as an acid. Such proteins are called acidic proteins. Most, of the blood proteins are acidic proteins., ,  Classification:, , A. On the basis of residues :, , 11, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , 1. Peptide: A molecule of protein made up of Only one amino acid, residue, 2. Dipeptide: A molecule of protein made up of Two amino acid, residues, 3. Tripeptide: A molecule of protein made up of Three amino acid, residues, 4. Polypeptide: A molecule of protein made up of Many amino acid, residues, B. On the basis of nature:, 1. Simple proteins: Proteins made up of only amino acids or their, derivatives called as simple proteins.,  Example: Histone protein (DNA), Zein protein (Maize),albumin, 2. Conjugated proteins: Proteins made up of amino acids with some, non protein (Prosthetic group) called as conjugated protein.,  Example:, 1. Lipoproteins, : Proteins + lipids, 2. Nucleoproteins : Proteins + Nucleic acid, 3. Glycoprotein, : Proteins + Glycogen, 4. Chromoprotein : Proteins + Chromogen pigment, On this basis, proteins are classified as, 1. Mucoproteins : carbohydrate-protein complexes, e.g. mucin of saliva and heparin of blood., 2. Lipopoteins : lipid-protein complexes, e.g. conjugate protein found in brain, plasma membrane, milk etc., 3. Derived proteins : These proteins are not found in nature as such., These proteins are derived from native protein molecules on hydrolysis., Example : Metaproteins, peptones are derived proteins, ,  Significance of protein :, , 1. Growth and development of body: Proteins helps in growth and, , development of body so also known as body building nutrients., 2. Acts as enzymes: All enzymes are proteins. Enzymes help in regulation of, metabolic activities., 3. Production of hormones: Proteins helps in production of hormones., Example : Growth /Somatotrophic hormone, Insulin, 4. Structural component of cells/Tissues: Proteins acts as structural units of, cells or tissues. [ Example: Keratin : Hair, Elastin : Connective tissue, Lipoprotein : Cell/Plasma membrane ], , 5. Acts as contractile protein: Muscles proteins acts as contractile, proteins. Example: Actin and Myosin protein, 6. Acts as Transport protein :Proteins helps in transportation, Example: Haemoglobin: Transportation of oxygen to cells, Myoglobin : Transportation of oxygen to muscles, 12, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , 7. Acts as defensive protein : Defensive proteins provides protection to, body against diseases, Example: Immunoglobulin: Antibody molecule provides immunity, Thrombin: Blood clotting factor helps in clotting of blood, 8. Helps in intracellular metabolism : Proteins helps in intracellular, metabolism, 9. Binding material between tissues : Proteins acts as binding material, between tissues, 10. Acts as source of energy in drastic body condition: Proteins acts, as source of energy in drastic body condition i.e. in deficiency of, carbohydrates and fats., , , , NUCLEIC ACID :, , o Definition: The macromolecules composed of many small units or, nucleotides (monomers) called as nucleic acid., Nucleic acid is largest macromolecule found in living beings, made up of nucleotides., o Nucleotides: The structural functional units of nucleic acids are, nucleotides. Nucleotides are composed of, Pentose sugar [ 5 carbon sugar ], Nitrogen bases, Phosphate group [ phosphoric acid], o Nucleotides are of two types, 1. Ribonucleotide: The nucleotide which contain ribose sugar., Ribonucleotide present in Ribose nucleic acid, 2. Deoxyribonucleotides: The nucleotide which contain Deoxyribose, sugar. Deoxyribonucleotides present in, Deoxyribose nucleic acid ., o Nucleoside: The combination of pentose sugar with nitrogen base, called as nucleoside., Nucleoside + phosphate group forms nucleotides which are, structural and functional units of nucleic acid, o Components of Nucleic acids :, 1. Sugar molecule : It is Pentose sugar contains 5 carbons., 2. Phosphate group/ Phosphoric acid [H3PO4] : The phosphate group, present in the form of phosphoric acid. Phosphoric acid contains 3, active –OH groups. Two active groups required for strand formation., Phosphoric acid attached to 5th carbon of Deoxyribose sugar., 3. Nitrogen bases: Nitrogen bases are cyclic compounds made up of C,, H, O and N atoms., , 13, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , 1. Purine base: It is double ring compound. Adenine & Guanine are, purine bases., 2. Pyrimidine base: It is single ring compound. Thymine and cytosine, are pyrimidine bases, , •, •, , Friedrich Miescher: Discovered nucleic acid., Nuclein: Acellular substance separated from nuclei of pus cells, termed as nuclein. Due to acidic nature of nuclein further termed as, nucleic acid., ,  TYPES OF NUCLEIC ACID :, 1. Deoxyribose nucleic acid, 2. Ribose nucleic acid, ,  Deoxyribose nucleic acid [ Watson and, Crick Model], , o Definition: The principal genetic material present in all organisms, except some viruses called as DNA., o Location: 98 % found in genes and 2 % found in mitochondria,, chloroplast and ribosome., o Nucleotides: The structural and functional units of nucleic acids, known as nucleotides. Nucleotides made up of 1 molecule of, deoxyribose sugar, one molecule of phosphate and one molecule of, nitrogen base. The nucleoside plus phosphate group forms, nucleotides., 14, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o Nucleosides: The combination of Deoxyribose sugar with nitrogen, base called as nucleosides. The nitrogen base attached to 1st carbon, molecule of sugar., o Double helix: Two long strands are coiled around a common, imaginary central /hypothetical axis and forms double helix. Double, helix means coiling twice like twisted ladder, , o Number of strands: Two long strands are present., o Structure of each strand: Each strand of DNA consists of number of, nucleotides. Successive nucleotides of the same strand linked by 3’-5’, phosphodiester bond i.e. one phosphate at 3rd carbon and another at, 5th carbon of sugar molecule, o Antiparallel strands: DNA strands are antiparallel i.e . one strand, placed in ascending direction and another strand in descending, direction., , 15, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , Clockwise/Right handed coiling: Two strands shows clockwise, /right handed coiling., o, Complementary strands: Base sequence present on one strand, decides base sequence of another strands known as complementary, strand, o Polarity of strands: Each strand of DNA has specific polarity. One, strand runs in 5’-3’ direction where as another in 3’-5’ direction., Polarity is due to 3rd and 5th carbon atoms of the Deoxyribose sugar., o 5’end: Free phosphate group., o 3’end: Free –OH group., o Arrangement of two strands: Strands are antiparallel i.e. 5’end of one, strand lies close to 3’end of other strand and vice versa., o Complementary base pairing: Nitrogen base present on one strand, pairs with nitrogen base of another strand., o A=T or T =A, G=C or C = G, o Adenine pairs with thymine and vice versa by two weak hydrogen, bonds. Guanine pairs with cytosine and vice versa by 3 weak hydrogen, bonds., o Purine : Pyrimidine ratio: Total number are purine bases is always, equal to total number of pyrimidine bases due to complementary base, pairing [ Chargaff’s law], o Rungs of ladder /Transverse bars: Nitrogen base pairing along with, hydrogen bonds forms rungs of ladder called as transverse bars. The, distance between two successive transverse bars is 0.34nm., SIGNIFICANCE OF DNA, 1., Heredity: DNA acts as units of heredity., 2., Mutation and Variations: DNA helps in mutation and variations., 3., Evolution: DNA helps in evolution., 4., Synthesis of RNA: DNA helps in synthesis of RNA by the process of, transcription., 5. Regulation of enzymes and proteins: DNA helps in regulation of, enzymes and proteins., 6. Controlling metabolic activities: DNA controls metabolic activities., 7. Master molecule of cell: DNA acts as master molecule of cell., 8. Power of replication: DNA has power of replication., 9. Transfer of genetic material: DNA helps in transfer of genetic, material., o, ,  RIBONUCLEIC ACID :, , o Definition: Single stranded polymer of nucleotide made up of ribose, sugar, phosphoric acid and nitrogen bases., o Number of strands: Single stranded structure, , 16, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o Nature : Simple and straight may be folded/coiled and forms normal, base pairing, o Location: Nucleus and cytoplasm., o Chemical components:, 1. Ribose sugar: Ribose sugar [C5H10O5] is pentose sugar and, pentagonal ring structure., 2. Phosphate group: Phosphate group present in the form of, phosphoric acid [H3PO4].It helps in linking of nucleotides during, strand formation., 3. Nitrogen bases: Nitrogen bases are cyclic compounds made up of C,, H, O and N atoms.,  Purine base: Adenine & Guanine are purine bases.,  Pyrimidine base: Uracil and cytosine are pyrimidine bases., o Base pairing: Base pairing present due to folding or coiling .Nitrogen, base present on one strand pairs with nitrogen base of another strand., Adenine pairs with uracil and vice versa by two weak hydrogen bonds., A=U or U =A, Guanine pairs with cytosine and vice versa by 3 weak hydrogen, bonds., G=C or C =G, o Purine : Pyrimidine ratio: May or may not be 1:1 [Base pairing not, fixed], o Bonds/Linkages: Long chains of nucleotides joined by phosphodiester bonds /linkages., o Folding : RNA strand is usually shows folding itself in certain regions ., Folding provide stability to RNA molecule., o Polarity :5’ to 3’ Most of RNA strand starts with adenine or guanine, TYPES OF RNA :, 1. Genetic RNA: The RNA which contains genetic material and acts as, carrier of heredity., Occurrence: TMV virus, HIV virus, Influenza virus, Reo virus and, wound tumor virus [ds RNA], 2. Non genetic RNA/Cellular RNA : The RNA which does not contain, genetic material and helps in protein synthesis known as non genetic, RNA. All non genetic RNA produced on DNA template by the process of, transcription and helps in protein synthesis in eukaryotes as well as, prokaryotes., Occurrence: All organisms except some viruses, ,  NON-GENETIC / CELLULAR RNA, 1. RIBOSOMAL RNA [rRNA] :, 17, , BIOCHEMISTRY OF CELL, , :, , 1. Ribosomal RNA [rRNA], 2.Messenger RNA [mRNA], 3.Transfer RNA [tRNA], , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o Definition: The RNA which provides proper binding site for m-RNA, and always associated with ribosome known as ribosomal RNA., o Nature : Simple and coiled upon itself., o Number of strands: Single stranded, o Base pairing: Folded region may show normal base pairing, o ... A= U /U=A and, o, G = C /C=G, o Length: Medium in length [ Shorter than m-RNA and larger than tRNA], o Molecular weight: 40,000 -1,00,000, o Constitutes: 80 % of the total RNA, o Ends: 5’end and 3’ end, o Synthesis: From DNA template with the help of enzyme DNA, polymerase enzyme, , Functions:, Provide proper binding site for m-RNA, Proper orientation of m-RNA for reading the codon[5’-3’ direction]\, Translation of coded information from m-RNA [primary decoding of, coded information], 4. Release of t-RNA after transfer of activated amino acids., 5. Production of structural proteins, 6. Protection of under constructed structural protein., o, 1., 2., 3., , 2. MESSENGER RNA [mRNA] :, , Definition : The RNA which carries coded message for protein, synthesis from DNA to ribosome called as m-RNA, o Nature : Always straight and simple without any fold, Number of strands: Single stranded structure, o, , 18, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , o, o, o, o, o, o, o, o, o, o, , o, o, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , Base pairing: Absent, Length: Longest RNA, Molecular weight: 5,00,000, Constitutes: 3-5 % of the total RNA, Ends: 5’end and 3’ end, Synthesis: From DNA template with the help of enzyme DNA, polymerase II by the process of transcription. Synthesis takes place in, nucleus and then comes in cytoplasm and associated with ribosome., Codon: The sequence of three nucleotides [triplet] on m-RNA is known, as codon. Each codon on m-RNA codes for specific amino acids called, as genetic code/m-RNA language /cryptogram., Start /Initiation codon: The codon present at 5’ end on m-RNA, called as start codon. Each start codon specifies a particular amino, acid. Initiation codon starts with AUG. [ In some cases start GUG ], Example: AUG: Specifies codes for methionine , GUG: Specifies codes, for valine and GGG: Specifies codes for glycine., Stop/Termination/Non sense codon: The codon present at 3’end of, m-RNA is called as stop codon. Stop codon does not specify any amino, acid hence called as non sense codon. Stop codon terminates, synthesis of polypeptide chain of amino acids so called as terminators., Example: 1. UAA: Ochre, 2. UAG: Amber, 3.UGA: Opal, Functions:, 1. Copies down coded information from DNA., 2. Carries coded information from DNA to ribosome., 3. Cryptogram/m-RNA language: The coded information present on, m-RNA known as cryptogram/genetic code., , 3. TRASNFER RNA [tRNA] :, , o Definition: The RNA which translates coded message of m-RNA and, helps in arrangement of amino acids in proper sequence called as, t-RNA., o Nature: Soluble RNA and cannot be easily separated from cytoplasm, even by centrifugation technique., , 19, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o Number of strands: Single stranded but shows two pattern of folding, upon itself., o Base pairing: Present, o Length: Smallest RNA, o Molecular weight: 23,000- 30,000, o Constitutes: 10-20 % of total cellular RNA, o Ends: 5’end and 3’ end, o Synthesis: From DNA template with the help of enzyme DNA, polymerase III by the process of transcription. Synthesis takes place in, nucleus and then comes in cytoplasm., o Hair pin model of tRNA :, , o Hair pin model: t-RNA folded in such a way that the hair pin like, structure formed [ Hoagland: Proposed hair pin model ], o Structure :, o Short arm: It present at 5’ end and it contains guanine nucleotide., o Long arm: Long arm present at 3’ end and ends at CCA nucleotides. It, is also c/a accepter end where amino acids are accepted., o Anticodon loop : The loop which contain anticodon., o Anticodon: Three unpaired nitrogen bases present at anticodon loop, called as anticodon. Anticodon /nodoc are complementary to codons, present on m-RNA, , o Clover leaf model of tRNA :, o, , Short arm: It is present at 5’end and ends at guanine. It contains, DHU /Amino acetyl synthetase loop/short arm loop., , o Middle arm: Middle arm contains anticodon loop /middle arm loop., Anticodon loop contains anticodon., 20, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o Extra arm: Additional small lump like arm is called as extra arm. It, contains variable loop., Long arm : Long arm present at 3’end and ends at CCA nucleotides. ., It contains ribosomal binding loop/TψC loop/long arm loop, , o, o, o, o, o, o, o, o, , 5’ end : Guanine nucleotide present, 3’end : cytosine-cytosine-Adenine[CCA] nucleotides present., Functions:, Transfers specific type of amino acid to ribosome [ at accepter end, Arrangement of amino acids in proper sequence., Providing recognition site [at CCA end], Translate coded message of m-RNA [ anticodon ], Attachment of specific amino acids to protein chain., ,  ENZYMES:, , o Definition: The specialized macromolecular proteinaceous substances, required for metabolic reactions called as enzymes., o Biocatalyst: Enzymes are biocatalyst which alters rate of biochemical, reactions., o Specialty: In living cells, metabolic reactions take place at normal, body temperature and pressure due to enzymes., o Substrate: The substance upon which an enzyme acts is termed as, the substrate., o Types of Enzymes:, 1. Endo enzymes: The enzymes produced within the body cell for, metabolic activities called as endo enzymes., o, e.g., enzymes produced in the chloroplast and mitochondria, , 21, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , 2. Exo enzymes: The enzymes produced within body cell and act away, from site of synthesis is called as exo enzymes., e.g., enzymes released by many fungi, , o Properties of Enzymes :, , 1. Nature of Enzymes: On the basis of chemical composition, enzymes, can be put into two categories., a. Purely proteinaceous enzymes, e.g .proteases that spilt protein, b. Conjugated enzymes : made up of a protein to which a nonprotein prosthetic group is attached.The prosthetic group is firmly, bound to the protein component by chemical bonds and, is not removed by hydrolysis. If the prostheticgroup is removed the, protein part of the enzyme becomes inactive., o There are enzymes which require certain organic compounds and, inorganic ions for their activity., 1] Coenzymes : The organic compounds that are tightly attached to, the protein part are called coenzymes., Example : Nicotinamide-adenine-dinucleotide (NAD) and Flavin, mononucleotide (FMN)., 2] Co-factors/ Enzyme activators : The inorganic ions which are, loosely attached to the protein part are called co-factors. Inorganic, ions of metals which act as co-factors include magnesium, copper,, zinc, iron, manganese etc., Iron (Fe++) is a co-factor of enzyme catalase, manganese is a co-factor of peptidases., 2. Proteinaceous Nature : All enzymes are basically made up of protein., 3. Three-Dimensional conformation: All enzymes have specific 3dimensional conformation. They have one or more active sites to which, substrate (reactant) combines. The points of active site where the, substrate joins with the enzyme is called substrate binding site., o Catalytic Property: Enzymes are like inorganic catalysts and, influence the speed of biochemical reactions but themselves remain, unchanged. After completion of the reaction and release of the product, they remain active to catalyze again.A small quantity of enzymes can, catalyze the transformation of a very large quantity of the substrate, into an end product., Example : sucrase can hydrolyze 100000 times of sucrose as compared, with its own weight., 4. Specificity of action: The ability of an enzyme to catalyze one specific, reaction and essentially no other is perhaps its most significant, property. Each enzyme acts upon a specific substrate or a specific, group of substrates., 22, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , 5. Reversibility of action : Enzymes are very sensitive to temperature, and pH., o Each enzyme exhibits its highest activity at a specific pH, called, optimum pH., o Any increase or decrease in pH causes decline in enzyme activity, o e.g. Enzyme pepsin (secreted in stomach) shows highest activity at, an optimum pH of 2 (acidic)., o Trypsin (in duodenum) is most active at an optimum pH of 9.5, (alkaline)., o Both these enzymes viz. pepsin and trypsin are protein digesting, enzymes., 6. Temperature :, o Enzymes are destroyed at higher temperature of 60-70°C or below,, they are not destroyed but become inactive., o This inactive state is temporary and the enzyme can become active, at suitable temperature., o Most of the enzymes work at an optimum temperature between, 20°C and 35°C., 7. Accelerate the reaction: Enzymes accelerates the reaction but do not, initiate the reaction, 8. No participation in reaction: Enzymes does not participate in reaction, and remains unchanged, 9. Required in small quantity: Enzymes required in small quantity, 10. Active site of enzyme: A specific part of enzyme molecule comes in, contact with substrate molecule is known as active site of enzyme, 11. Amphoteric nature: Enzymes can react with acidic as well as, alkaline substances., 12. Specificity: Most of the enzymes are specific in action., 13. Example: Invertase: Sucrose, Urease: Urea Lipase: Lipids, 14. Colloidal nature: Colloids are gel substance contains mixture of, dispersed particles and dispersion medium. The size of dispersed, particles is larger than dispersion medium., 15. Provides large surface area for reaction: Due to colloidal nature,, enzymes provide large surface area for reaction., 16. Enzyme optima: Enzymes works best under appropriate, temperature and pH called as enzyme optima., , , , Nomenclature of Enzymes: There are various ways of, , naming enzymes., o Enzymes are named by adding the suffix-‘ase’ to the name of the, substrate on which they act e.g. protease, sucrase, nuclease etc. which, break up proteins, sucrose and nucleic acids respectively., 23, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o The enzymes can be named according to the type of function they, perform e.g. dehydrogenase remove hydrogen, carboxylase add CO;, decarboxylases remove CO2, oxidases helping in oxidation., o According to international code of enzyme nomenclature, the name of, each enzyme ends with an -ase and consists of double name., o The first name indicates the nature of substrate upon which the, enzyme acts, o The second name indicates the reaction catalysed, o e.g. pyruvic decarboxylase catalyses the removal of CO2 from the, substrate pyruvic acid. Glutamate pyruvate transaminase catalyses the, transfer of an amino group from the substrate glutamate to another, substrate pyruvate., , Classes of enzymes :, S.N., , Type of enzyme, , Action, /Function, , Examples, , 1 Oxidoreductase Catalyze oxidation, /Dehydrogenase reduction[ Transfer, electrons or hydrogen, atoms from one, molecule to another], , S.N. Type of, enzyme, , S.N., , Examples, o Hexokinase, o Transaminase, o Glucokinase, , Transfer of chemical, group between a pair of, substrate [ moving, functional group from one, molecule to another], , Type of, enzyme, Hydrolases, , 24, , Action /Function, , Transferase, , 2, , o NAD oxido reductase, o Cytochrome oxidases, o alcohol, dehydrogenase, , Action /Function, Catalyze hydrolysis of, esters ,ether, peptide,, glycosidic & C-C bonds [, catabolic ], , BIOCHEMISTRY OF CELL, , Examples, o, o, o, o, , Lipase, Protease, Choline esterase, Alkaline phosphatases, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , S.N. Type of, enzyme, Lyases, , 4, , LECTURE NOTES BIOLOGY, , Action /Function, , Examples, , Catalyze non hydrolytic cleavage [, Splitting chemicals into smaller parts, without using water] These enzymes, are involved in elimination reactions, resulting in the removal of a group of, atoms from substrate molecule, to leave a double bond., , S., N., , Type of, enzyme, , 5, , IsoCatalyze inter conversions of, merases geometric, optical and, positional isomers, [ Catalyze rearrangement of, atoms with in a molecule ], , S, N, , Type of, enzyme, , 6, , Ligase /, Synthetase, , , , XI SCIENCE, , Action /Function, , o, o, o, o, , Aldolase, Fumarase, Decarboxylases, Dehydratases,, , Examples, o, o, o, o, o, , Triose phosphor- isomerase, Phospho hexo isomerase., Racemases, Epimerases, Xylose isomerases,, mutases, , Action /Function, , Examples, , Joining of two molecules by the, formation of new bonds., [Anabolic] catalyse the covalent, linkage of the molecules, utilizing the energy obtained, from hydrolysis of an energyrich compound like ATP, GTP., , o, o, o, , DNA ligase, DNA polymerase, Acetyl Coenzyme, Carboxylase, o, Succinate thiokinse, o Glutathione Synthatase, o Pyruvate carboxylase, , Enzyme action/Catalytic cycle :, , o The basic mechanism by which enzymes catalyze chemical reactions, begins with the binding of the substrate (or substrates) to the active, site on the enzyme., , 25, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , The active site is the specific region of the enzyme which combines, with the substrate., o The binding of the substrate to the enzyme causes changes in the, distribution of electrons in the chemical bonds of the substrate and, ultimately causes the reactions that lead to the formation of, products., o The products are released from the enzyme surface to regenerate the, enzyme for another reaction cycle., o Enzyme action /Catalytic cycle :, o, , , , Induced fit Model:, , o Koshland (1959) proposed the induced fit theory, which states that, approach of a substrate induces a conformational change in the, enzyme., o It is the more accepted model to understand mode of action of enzyme., o Unlike the lock-and-key model, the induced fit model shows that, enzymes are rather flexible structures in which the active site, continually reshapes by its interactions with the substrate until the, time the substrate is completely bound to it., o It is also the point at which the final form and shape of the enzyme is, determined, 26, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , o The action of enzyme (lock) with single substrate (Key) is lock key, analogy., o Enzyme substrate complex (ES) : The substrate (S) binds to the active, site of enzyme (E) and forms ES complex., o Due to ES complex, enzyme alters its shape and fits more tightly, around substrate., o Active site breaks the chemical bonds of substrate and new enzyme, product (EP) complex formed., o Enzyme releases the product and becomes free., o Free enzyme now ready to bind another molecule of substrate and, repeat the cycle., , o Factors Affecting Enzyme Activity :, , 1. Concentration of Substrate : Increase in the substrate, concentration gradually increases the velocity of enzyme activity, within the limited range of substrate levels. A rectangular hyperbola, is obtained when velocity is plotted against the substrate, concentration. Three distinct phases (A, B and C) of the reaction are, observed in the graph., Where V = Measured velocity, Vmax = Maximum velocity, S =, Substrate concentration, Km = Michaelis-Menten constant., The activity of enzymes is reduced at low temperature. The, temperature at which the enzymes show maximum activity is called, Optimum temperature., o Concept of Metabolism: Metabolism is the sum of the chemical, reactions that take place within each cell of a living organism and, provide energy for vital processes and for synthesizing new organic, material. It involves continuous process of breakdown and synthesis, of biomolecules through chemical reactions. Each of the metabolic, reaction results in a transformation of biomolecules. Most of these, metabolic reactions do not occur in isolation but are always linked, with some other reactions.In living systems, cells are ‘work centres’, where metabolism involves two following types of pathways, a. Catabolic pathways lead to formation of simpler structure from, a complex biomolecules e.g. when we eat wheat, bread or chapati,, our gastrointestinal tract digests (hydrolyses) the starch to, , 27, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , glucose units with help of enzymes and releases energy in form of, ATP (Adenosine triphosphate)., b. Anabolic pathway is called biosynthetic pathway that involves, formation of a more complex biomolecules from a simpler, structure, e.g., synthesis of glycogen from glucose and protein, from amino acids. These pathways consume energy, Metabolic pool :, It is the reservoir of biomolecules in the cell on which enzymes can, act to produce useful products as per the need of the cell. The, concept of metabolic pool is significant in cell biology because it, allows one type of molecule to change into another type e.g., carbohydrates can be converted to fats and vice-versa, .Catabolic chemical reaction of glycolysis and Krebs cycle only, provide ATP but also makes available metabolic pool of biomolecules, that can be utilized for synthesis of many important cellular, components. The metabolites can be added or withdrawn from this, pool according to the need of the cell. The balance between, catabolism and anabolism maintain homeostasis in the cell as well, as in the whole body., 4. Effect of pH :Similar to temperature, there is also pH at which an, enzyme will catalyze the reaction at the maximum rate. Every, enzyme has different optimum pH value. The enzyme cannot, perform its function beyond the range of its pH value., 5. Other Substances :The enzymes action is also increased or, decreased in the presence of some other substances such as coenzymes, activators and inhibitors. Most of the enzymes are, combination of a co-enzyme and an apo-enzyme. Activators are the, inorganic substances which increase the enzyme activity. Inhibitor, is the substance which reduces the enzyme activity., o Secondary metabolites (SMs) :, Secondary metabolisms are small organic molecules produced by, organisms that are not essential for their growth, development and, reproductions. Several types of bacteria, fungi and plants produce, secondary metabolism. Secondary metabolites can be classified on, the basis of chemical structure (e.g. SMs containing rings, sugar),, composition (with or without nitrogen), their solubility in various, solvents, or the pathway by which they are synthesized, (e.g.phenylpropanoid produces tannins). A simple way of classifying, secondary metabolites includes three main groups such as, 1., Terpenes : Made from mevalonic acid that is composed mainly of, carbon and hydrogen2. Phenolics : Made from simple sugars, containing benzene rings, hydrogen and oxygen.3. Nitrogen-containg, compounds : Extremely diverse class may also contain, sulphur.Economic importance –, Secondary metabolites :, , 28, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE

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MAURYA SCIENCE ACADEMY, , LECTURE NOTES BIOLOGY, , XI SCIENCE, , 1. Secondary metabolites from natural sources have made a, significant contribution for millennia. In modern medicine, drugs, developed from secondary metabolites have been used to treat, infectious diseases, cancer, hypertension and inflammation., 2. Morphine was the first alkaloid isolated from plant Papaversomnif, erum. It is used as pain reliever and cough suppressant., 3. SMs like alkaloids nicotine and cocaine and the terpenes, cannabinol are widely used for recreation and stimulation., 4. Flavours of secondary metabolites improve our food preference., 5. Characteristic flavours and aroma of cabbage and its relatives are, caused by nitrogen and sulphur-containing chemicals,, glucosinolates, protect these plants from many pests., 6. Tannins are added to wines and chocolate for improving, astringency., 7. Since most of secondary metabolites are having antibiotic, properties, they are also used as food preservatives., , 29, , BIOCHEMISTRY OF CELL, , |SIGN OUT BY DR. VIRESH SHELKE