© 2003 Thomson Learning, Inc. All rights reserved General, Organic, and Biochemistry, 7e Bettelheim, Brown, and March

© 2003 Thomson Learning, Inc. All rights reserved Chapter 29 Nutrition and Digestion Nutrition and Digestion

© 2003 Thomson Learning, Inc. All rights reserved Nutrition Nutrients: Nutrients: the components of food and drink that provide growth, replacement, and energy 1. carbohydrates 2. lipids 3. proteins 4. vitamins 5. minerals 6. water Digestion: the hydrolysis of starches, fats, and proteins into smaller units

© 2003 Thomson Learning, Inc. All rights reserved The Food Guide Pyramid

© 2003 Thomson Learning, Inc. All rights reserved Calories Nutritional calorie (Cal): Nutritional calorie (Cal): 1000 cal or 1 kcal Basal caloric requirement: Basal caloric requirement: the energy requirement for a resting body

© 2003 Thomson Learning, Inc. All rights reserved Carbohydrates Carbohydrates are the main source of energy in a diet; the main dietary carbohydrates are the polysaccharide starch the disaccharides lactose and sucrose the monosaccharides glucose and fructose Digestion of carbohydrates starts in the mouth  -amylase catalyzes the hydrolysis of  -1,4-glycosidic bonds  -amylase catalyzes the hydrolysis of  -1,4-glycosidic bonds debranching enzymes catalyze the hydrolysis of  -1,6- glycosidic bonds

© 2003 Thomson Learning, Inc. All rights reserved Fats Fats are the most concentrated source of energy lipases, the enzymes that catalyze the hydrolysis of lipids, are located in the small intestine bile salts, synthesized in the liver and stored in the gallbladder, emulsify water-insoluble dietary fats so that they can be acted upon by lipases fats are hydrolyzed to fatty acids, and complex lipids to fatty acids, alcohols, and carbohydrates

© 2003 Thomson Learning, Inc. All rights reserved Proteins Although dietary proteins can be used for energy, their main use is to furnish amino acids from which the body can synthesize its own proteins digestion of proteins begins with cooking, which denatures proteins and makes it easier for the digestive enzymes and HCl of the stomach to hydrolyze them most protein digestion occurs in the small intestine the 10 essential amino acids must be obtained from the diet complete protein:complete protein: a dietary protein that contains all essential amino acids

© 2003 Thomson Learning, Inc. All rights reserved Proteins gelatin, which is denatured collagen, is an incomplete protein because it lacks Trp, and is low in Ile and Met corn protein is low in Lys and Trp wheat protein is low in Lys legumes are low in Met soy protein is very low in Met Protein complementation: Protein complementation: a diet in which two or more proteins complementation each other’s deficiencies; for example: grains + legumes

© 2003 Thomson Learning, Inc. All rights reserved Vitamins and Minerals See Table 29.1 for sources, functions, deficiency diseases, and daily requirements of vitamins and minerals

© 2003 Thomson Learning, Inc. All rights reserved End Chapter 29 Nutrition and Digestion