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First Semester B.Sc. Psychology- PSG1C01: Human Physiology –Cellular organization, , CELL INCLUSIONS, Cell inclusions are considered various nutrients or pigments that can be found, within the cell, but do not have activity like other organelles. Examples of cell inclusions, are glycogen, lipids, and pigments such as melanin, lipofuscin, and hemosiderin., Glycogen, Glycogen is the long-term storage unit of glucose within the cell, typically in liver, and muscles. Glucose molecules are connected by α(1-4) linkages and branched off by, α(1-6) linkages to form the complex structure of glycogen, which also aids in rapid, breakdown. Glycogen can be visualized in tissue using a periodic acid-Schiff (PAS) stain., Under an electron microscopic, two forms of glycogen exist. The first is a single, spherical 15-30 nm particle (β–particle) that stain densely with lead. The second are, aggregates of small particles (β-particles) called rosettes (α-particle)., Lipids, Lipid spheres in tissues are caused by an accumulation of triglycerides and, appear as perfectly spherical structures. Due to processing, lipids cannot be visualized, in paraffin-embedded tissues; it is assumed lipid was present when clear, spherical, structures are present. On frozen tissue, lipids can be visualized using stains such as, Sudan Black or Oil Red O. The material is prominent in adipocytes (fat cells), and may be, found in any cell. The quantity varies with metabolic state., Pigments, Numerous pigments can be observed in tissues and cells. Melanin is a brown, pigment in hair and skin and is contained in melanosomes. These are dense ellipsoidal, granules produced by specialized cells called melanocytes and are transferred to hair, and skin cells to produce a pigmentary change., A second pigment often found in cells and tissues is lipofuscin. Lipofuscin often, appears as a brown-yellow colour that can be auto-fluorescent and accumulates over, time, giving it the name “age pigment”. It is mainly found in the lysosomes of postmitotic cells. Accumulation of lipofuscin can have detrimental effects on the cell by, disturbing cellular processes and leading to a degradation of cellular activity. A third, pigment is hemosiderin, which is a brown pigment that contains iron. When hemoglobin, Shibu Abdullah, Amal College of Advanced Studies, NIlambur, , 1

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First Semester B.Sc. Psychology- PSG1C01: Human Physiology –Cellular organization, , breaks down, the products are phagocytized by macrophages and accumulate within the, cell. Excessive hemosiderin accumulation may indicate an increase in hemolysis of red, blood cells., Structure of carbohydrates, Carbohydrates are the basic energy source in animal cells. Dietary carbohydrates, obtained from plant-based products serve as a major source of energy for the animal., Carbohydrates are chemical molecules which contain carbon (C), Hydrogen (H) and, Oxigen (O). The general formula of carbohydrates is CnH2nOn. In other words, the ratio, of carbon to hydrogen to oxygen is 1:2:1 in carbohydrate molecules. This formula also, explains the origin of the term “carbohydrate”: the components are carbon (“carbo”), and the components of water (hence, “hydrate”). Carbohydrates are classified into three, subtypes:, 1. Monosaccharides, 2. Disaccharides, 3. Polysaccharides, Monosaccharides, Monosaccharides are often referred to as simple sugars (e.g., glucose) and cannot, be hydrolyzed into simpler compounds. Monosaccharides can be subdivided based on, the number of carbon atoms. The following list shows the prefixes for numbers of, carbons in a sugar., 1. Triose (3 C), 2. Tetrose (4 C), 3. Pentose (5 C; e.g., Xylose and Ribose), 4. Hexose (6 C; e.g., glucose, fructose, galactose, and mannose), The three hexoses that are nutritionally and metabolically important are glucose,, fructose, and galactose. Glucose is the form of carbohydrates found in circulating blood, (blood sugar) and is the primary carbohydrate used by the body for energy production., Fructose, or “fruit sugar,” is found in ripened fruits and honey and is also formed by, , Shibu Abdullah, Amal College of Advanced Studies, NIlambur, , 2

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First Semester B.Sc. Psychology- PSG1C01: Human Physiology –Cellular organization, , digestion of disaccharide sucrose. Galactose is found along with disaccharide lactose in, mammalian milk and is released during digestion., , Disaccharides, Disaccharides are made up of two monosaccharides bonded together by a, glycosidic (covalent) bond. The following are some of the common disaccharides:, 1. Sucrose, , -glucose + fructose (e.g., table sugar), , 2. Lactose, , -glucose + galactose (milk sugar), , 3. Maltose, , -α-D-Glucose + β-D-Glucose (malt sugar), , 4. Cellobiose, , -β-D-Glucose + β-D-Glucose (cellulose), , Among the different disaccharides, lactose (milk sugar) is the only carbohydrate, of animal origin. However, cellobiose as a component of cellulose is important in animal, nutrition., Oligosaccharide, Oligosaccharide are made by bonding together three or more (3 to 15), monosaccharides bonded together. Eg: Raffinose (glucose + fructose + galactose), Stachyose (glucose + fructose + 2 galactose). In animal diets, oligosaccharides are, commonly found in beans and legumes., Polysaccharides, Polysaccharides are the most important carbohydrate in animal feed. As their, name implies, polysaccharides are made by joining together large polymers of simple, sugars. Polysaccharides are composed of many single monosaccharide units linked, together in long, complex chains. The functions of polysaccharides include energy, storage in plant cells (e.g., seed starch in cereal grains) and animal cells (e.g., glycogen), Shibu Abdullah, Amal College of Advanced Studies, NIlambur, , 3

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First Semester B.Sc. Psychology- PSG1C01: Human Physiology –Cellular organization, , or structural support (plant fiber). Components of cell wall structure are also called, non-starch polysaccharides, or resistant starch, in animal nutrition, as they cannot be, digested by animal enzymes but are fermented by hindgut and rumen microbes., Structure of Lipids, After carbohydrates, lipids serve as a major source of energy in animal diets., Lipids (also known as fats) are components of plant (e.g., vegetable oils) and animal, tissues (e.g., meat, eggs, milk). On a physical nature, lipids are relatively insoluble in, water and are soluble in organic solvents, such as hexane, ether, and chloroform., Chemically, lipids are organic compounds and esters of fatty acids and glycerol (3 C, compound) or some other alcohol. Basically lipids are esters of fatty acid with alcohol,, e.g. 1 glycerol + 3 fatty acids (commonly called triglyceride)., Simple lipids like triglycerides are more common and are an important, component in animal rations (e.g., vegetable oil and animal fats such as tallow or lard)., Compound lipids are composed of a lipid plus a nonlipid molecule (e.g., protein)., Lipoprotein (lipid + protein) are examples of compound lipids and are used for lipid, transport (like a courier). Within the animal body, compound lipids are more important, in physiology and metabolism (e.g., lipid transport, phospholipids as part of cell, membranes)., Structure of Protein, Proteins are large biological molecules. Proteins are organic compounds made, up of different building blocks (basic units) called amino acids joined together by, peptide bonds. A dipeptide contains one peptide bond and two amino acids, whereas a, tripeptide contains three amino acids and two peptide bonds. A peptide with more than, ten amino acids is called a polypeptide. Proteins are essentially large polypeptides. The, structure of a protein is determined first by the sequence of individual amino acids it, has in the polypeptide chain. This is also called the primary structure of the protein., Like other biological macromolecules proteins are essential parts of organisms, and participate in every process within the cell. Many proteins are enzymes and, hormones. The form the structural frame work of the cell and the body. They form the, immune cells. It perform a vast array of functions within living organisms., , Shibu Abdullah, Amal College of Advanced Studies, NIlambur, , 4