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Download CARBOHYDRATES Carbohydrates are made up of carbon
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CARBOHYDRATES Carbohydrates are made up of carbon, hydrogen and oxygen only. They are classified according to the number of the simple units they contain as; a) Monosaccharides: (simple sugars) They have the general formula C6H12O6. Examples are glucose, fructose (found in juicy fruits) and galactose (milk sugar). They have the following general physical properties; i. Sweet taste ii. Dissolve in water iii. Can diffuse through a semi permeable membrane b) Complex sugars These are sugars composed of two or more monosaccharide molecules. Complex sugars are of two types; i) Disaccharides General formula C12H22O11 Formed by the process called condensation. i.e. chemical combination process that results in loss of water molecule. Example Glucose + maltose + C6H12O6 + condensation water + C12H22O11 Glucose C6H12O6 condensation H2O The disaccharides may be reconverted back to monosaccharides by a process called hydrolysis. Hydrolysis involves the addition of water in a chemical breakdown of larger molecules into smaller forms. 1 https://cmbiologynotes.wordpress.com Disaccharides have the following properties a) Sweet taste b) Colourless crystalline substance c) Soluble in water d) Less diffusion across a semi permeable membrane compared to monosaccharides ii) Polysaccharides: These are formed by further condensation of more than two molecules of monosaccharides. They have the general formula (C6H10O5)n where n represents several sugars. Polysaccharides include the following; a) Starch, stored in plant parts such as cassava, potato, and root tubers. b) Glycogen: stored form of carbohydrate in animals mainly in muscle and liver c) Cellulose, found in plant cell walls. It consists of a long chain of glucose. They have the following general characteristics; a) Insoluble in water b) Cannot diffuse across a semi permeable membrane c) They are not sweet Functions of carbohydrates 1. Energy production during respiration 2. Formation of structures such as cell walls of plants made of cellulose 3. Cellulose is used in the manufacture of papers, synthetic fibers, films and explosives. 2 https://cmbiologynotes.wordpress.com PROTEINS Proteins are body building foods. They are made up of carbon, hydrogen, nitrogen, oxygen and sometimes sulphur and phosphorus. Compared with most other organic molecules, protein molecules are huge and therefore cannot pass through semi-permeable membrane. Proteins are made up of small unit molecules called amino acids. The nature of protein is determined by the types of amino acids it is made of. Amino acids have the general formula H R C COOH NH2 _ amino group NH2 There are about 20 amino acids that make up proteins in living organisms. TYPES OF AMINO ACIDS There are two types of amino acids; 1. Essential amino acids. These are amino acids that can not be synthesized by the body and have to be supplied in the diet. Examples are valin, arginine, leusin, lysine, phenydalanine etc. there are 10 essential amino acids. 3 https://cmbiologynotes.wordpress.com 2. Non essential amino acids. These are the amino acids which can be synthesized by the body and therefore need not to be available in the died.exaples include glycine, alanine, asparticacid, serine, praline etc. There are also 10 non essential amino acids. CLASSIFICATION OF PROTEINS Proteins can be classified into two, 1. First class proteins. These are the proteins that contains all the essential amino acids e.g. soya beans, and most animal proteins. 2. Second class proteins. These are proteins that lack one or more of the essential amino acids. They include mostly plant proteins and a few animal proteins FORMATION OF PROTEINS Proteins are made up of many amino acid units joined together through peptide bonds. When two amino acids are joined together a dipeptide is formed. The chemical process involved is called condensation in which water is formed or lost. When many amino acids are joined together a polypeptide chain is formed. The nature of a particular protein depends on the types and sequence of amino acids from which it is made. PROPERTIES OF PROTEINS 1. Dissolve with difficulty in water to form colloidal solution (sticky like glue) 2. They have large molecules and so cannot pass through cell membranes. 3. Proteins coagulate when boiled. This is what happens when the egg albumen is boiled. 4 https://cmbiologynotes.wordpress.com FUNCTIONS OF PROTEINS 1. Vital for the formation of new cells and replacement of old ones hence growth. 2. They help in maintaining the composition of protoplasm. 3. They are used in the formation of various structures in the body eg keratin in the hair, nails, hooves, horns, feathers etc. 4. They are important in the formation of enzymes, which speed up chemical reactions in organisms.. 5. They form antibodies which defend the body against diseases. 6. Coordination of activities in the body as a hormone constituent. 7. Proteins may be used for respiration in circumstances where carbohydrates and lipids are not present. Deficiency of proteins causes a disease called kwashiorkor. Occurs normally in children between ages of 6 months and 4 years because of the high energy requirement and growth after weaning. VITAMINS Vitamins are organic constituents of food that are required in small amounts for a variety of metabolic processes. They often form part of enzymes. Vitamins are of two groups, i.e. water soluble and fat soluble vitamins. Fat soluble vitamins include A, D, E, and K. water soluble vitamins include B and C VITAMIN FOOD SOURCES FUNCTIONS DEFICIENCY AND SYMPTOMS. A Animal fat and Normal growth. Poor night vision RETINAL oils, milk, liver, Keeps skin and [xeropthalamia] or green vegetables, eyes healthy. night blindness. carrots, green Increases Poor growth. 5 https://cmbiologynotes.wordpress.com paper. resistance to Reduced disease. resistance to diseases. B1 Yeast, egg, liver, As a coenzyme in Disease of the THIAMINE pulses, cell respiration for muscles, nerves Tomatoes, the normal and heart. unpolished functioning of the Loss of appetite. cereals. heart and Circulatory failure. nerveous system Paralysis. Digestive trouble. Wasting away of the muscles. Poor assimilation loss of weight. B2 Meat, milk, other RIBOFLAVIN as for B1 For cell Slow growth respiration Skin diseases For skin health Sore mouth. PELLAGRA PP Meat, fish, wheat, For cell NIACINICOT eggs, liver, green, respiration INIC ACID vegetatables. - A skin disease - Mental disorder - Abdominal pains - Diarrhea - Pigmentation in exposed areas of the chest C Fresh citrus fruits, - Ascorbic acid green vegetables, Increased SCURVY resistance Irish potatoes - - Pains and to disease swelling of the Formation joints and 6 https://cmbiologynotes.wordpress.com of collagen - gums, Healing of - wounds Loosening of teeth, bleeding of the gums, skin and mucous membranes - Poor wound healing - General weakness D Milk, eggs, fish, Hardening of RICKETS Calciferol liver, oil and bones and teeth (faulty bone formation E butter. in children) Skin of man in Teeth diseases sunlight (dental caries) Vegetable oil, (Tocopherol) eggs, liver Promotes fertility Sterility in animals (in rats) e.g. rats K Green vegetables, Clotting of blood Delayed clotting of Phyloquinon tomatoes and liver blood e Mineral elements These are in organic food constituents required by the body in small amounts but their deficiency affects the functioning of the body leading to a deficiency disease or symptom Mineral elements can be grouped into 7 https://cmbiologynotes.wordpress.com - Essential mineral elements; i.e. those required in large amounts and include; Na, P, K, Ca and Fe - Non essential mineral elements; these are required in small amounts and include; Zn, Mo, Co, B and Mn. They are also called trace elements. Table 3.4 Giving facts about some of the mineral elements required by man MINERAL FOOD ELEMENT SOURCES IRON CALCIUM IMPORTANCE DEFFICIENCY Beef, liver, Constituent of Reduced red kidney, green haemoglobin blood cell count vegetables, G and oxygen nuts, cocoa, transport resulting beans, eggs. in ANAEMIA Vegetables, fish, Constituent of milk, bread, bones and teeth eggs. which it is responsible for hardening For muscle contraction. For clotting of blood. Activator of enzymes. 8 https://cmbiologynotes.wordpress.com RICKETS DELAYED MUSCLE CONTRACTION PHOSPHOROUS Most foods Formation of Not likely to be (dairy products, ATP. deficient since it is meat, fish, poultry, nuts.) FORMATION OF BONES AND TEETHS present in most foods especially protein Constituent of cell membranes IODINE SODIUM Sea fish, iodized Constituent of the GOITRE (swelling salts. hormone of the thyroid thyroxine. glands) Transmission of MUSCLE CRUMP nerve impulses (i.e. sharp pains in Common salt. Muscle muscles) contraction FLUORINE Added to Constituent of Weak teeth (in drinking water. bones and teeth. children). Prevents dental carries 9 https://cmbiologynotes.wordpress.com