Chapter 6: Proteins PDF

6 Proteins  Facts Of the six nutrient groups, only proteins can make new cells and Protein rebuild – large tissue.molecules that works in cell and complex Proteins...

6 Proteins  Facts Of the six nutrient groups, only proteins can make new cells and Protein rebuild – large tissue.molecules that works in cell and complex Proteins required forare theessential structurethroughout theregulation ,function and entire lifespan. of body Proteins are the basic material tissues of every body cell. and organs Proteins are the only nutrient group that contains nitrogen. 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Amino Acid (building blocks of protein) Ex: found in beef, poultry and eggs Proteins are composed of amino acids. Amino acids are nitrogen-containing compounds. Essential amino acids must be provided by the diet. There are 8 essential amino acids and 2 that are essential during childhood only. Nonessential amino acids can be produced by the body. 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Classification Complete amino acid (complete protein) Foods include beef,poultry,fish, egg and dairy High quality Contains all 10 essential amino acids Incomplete amino acid Food include nut,seed beans,rice and veggies Lacks one or more amino acids Cannot build tissue without help 6-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Classification Complementary proteins (2 incomplete sets of protein that can be consumed separately) Occur when a combination of incomplete proteins are eaten in the same day to make a complete protein Examples: corn and beans, rice and beans, bread and peanut butter, bread and split pea soup, bread and cheese, bread and baked beans, macaroni and cheese, cereal and milk 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Food Sources Animal food sources Complete proteins. Meats, fish, poultry, eggs, milk, and cheese Plant food sources Incomplete proteins Corn, grain, nuts, sunflower seeds, sesame seeds, and legumes (beans) 6-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Food Sources Analogues (Replacer or Alternative) Meat alternatives made from soy protein and other ingredients to simulate various kinds of meat Tofu is a soft, cheeselike food made from soy milk Helpful to strict vegetarians to meet their protein needs 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Functions Building and repairing body tissue Regulating body functions Metabolism and digestion Fluid and electrolyte balance Development of antibodies Providing energy Each gram of protein provides 4 calories. 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Digestion and Absorption Mechanical digestion Begins in mouth Teeth grind food into small pieces. Chemical digestion Begins in stomach Hydrochloric acid prepares stomach The enzyme pepsin reduces proteins to polypeptides. 6-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Digestion and Absorption Chemical digestion Polypeptides: 10 or more amino acids bonded together In the small intestine, three pancreatic enzymes (trypsin, chymotrypsin, and carboxypeptidase) continue chemical digestion and absorption through the villi. 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Metabolism and Elimination Amino acids are broken down and the nitrogen-containing amine group is stripped off. Ammonia is produced. Liver picks up ammonia and converts it to urea. 6-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Metabolism and Elimination Liver picks up ammonia and converts it to urea. Kidney filters out urea and excretes it. Remaining parts are used for energy or converted to carbohydrate or fat and stored as glycogen(substance in bodily tissues as stored of carbohydrates) or adipose tissue. 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Dietary Requirements To determine your requirement: 1. Divide body weight by 2.2 (the number of pounds per kilogram). 2. Multiply the answer obtained in the first step by 0.8 (grams of protein per kilogram of body weight). 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Protein Excess (poultry ,eggs, beans and shellfish) Saturated fats and cholesterol found in complete proteins may contribute to heart disease Connection to colon cancer Substitute for essential fruits and vegetables 6-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Protein Excess Increased demand on kidneys National Research Council recommends that protein intake represent no more than 15%–20% of one’s daily caloric intake and not exceed double the amount given in the table of Recommended Dietary Allowances. 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Protein Deficiency Muscle wasting (thinning or loss of muscle tissue) occurs. Albumin (protein in blood plasma) deficiency causes edema. Loss of appetite, strength, and weight Lethargy,(state of feeling drowsy) depression, and slow wound healing 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Protein Energy Malnutrition (PEM) Lack protein and energy-rich foods Found in developing countries with shortages of protein and energy-rich foods Causes stunted(prevented from growing)growth in children Mental retardation may occur in infants born from mothers with protein deficiency. 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Marasmus (severe undernourishment) Affects very young children Results from severe malnutrition (lack of energy, protein, vitamins, and minerals) Emaciated(thin/weak) no edema Hair is dull and dry; skin is thin and wrinkled 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Kwashiorkor-forms of malnutrition caused by protein deficiency in children Sudden or recent lack of protein- containing food; affects children and adults Fat accumulates in the liver, and lack of protein and hormones results in edema, painful skin lesions, and changes in pigmentation of skin and hair High mortality rate 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Conclusion Proteins contain nitrogen. They build and repair body tissues, regulate body processes, and supply energy. Each gram of protein provides 4 calories. Proteins are composed of amino acids. Ten of the amino acids are essential for growth and development. 6-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.