Chapter Four: Proteins and Amino Acids

1. Chapter Four: Proteins and Amino Acids • Explain how the chemical structure of proteins differs from the other energy nutrients • Identify and describe the multiple functions of protein in the body • Explain the difference between essential and non-essential amino acids • Describe the concept of nitrogen balance

2. Proteins cntd. • Describe conditions associated with either positive or negative nitrogen balance • Describe causes and characteristics of marasmus and kwashiorkor • Explain what makes a protein complete and identify sources of them • Explain the types of vegetarian diets

3. What do you already know? • Proteins in Review • Energy provided: 4 kcal per gram • 12-15% of calories per day • Sources in the Food Guide Pyramid • Bread, Cereal, Rice and Pasta Group • Vegetable Group • Milk, Yogurt and Cheese Group • Meat and Meat Alternates Group

4. Chemical View of Protein • Contains same elements as other energy nutrients (carbon, hydrogen and oxygen) plus nitrogen • Made up of building blocks called amino acids (20 amino acids) • Essential amino acids must be supplied in foods (9 are essential) • Non-essential am. acids—body can make

5. Nutritional Role of Proteins • Primary function is to Build, Maintain, and Repair the Body — not to provideenergy • Enzymes: catalysts that facilitate chemical reactions • Anabolic—build body compounds • Catabolic—dismantle body compounds • Example—digestive enzymes

6. Nutritional Roles cntd. • Fluid and Electrolyte Balance • Help maintain distribution of fluids in the body • Proteins are hydrophilic—water loving • Acid-Base Balance • Controls blood pH (acidity or alkalinity) • Release or bind hydrogen ions

7. Protein roles cntd. • Antibodies • Formed from protein • Maintains resistance to disease • Hormones • Messenger molecules • Examples are insulin and thyroxin • Transport—carry other nutrients, e.g. oxygen, lipids, vitamins and minerals

8. Protein Roles cntd. • Nitrogen Balance—maintenance of same amount of protein in body tissues • Positive Balance—nitrogen in > nitrogen out • Growing children • Pregnant woman • Negative Balance—nitrogen in < nitrogen out • Fasting or starvation • Severe traumas—burns, tissue loss

9. Protein Roles cntd. • Zero balance • Nitrogen in = nitrogen out • Normal daily functioning • Measured by sample of body tissue or urine

10. Protein Deficiency • Marasmus • Energy deficiency common in young children ages 6-18 months • Food is low in kcalories and protein • Kwashiorkor: (Red hair) • Protein deficiency common in children after age two—after weaning • Symptoms: edema, distended abdomen and orange hair

11. Proteins in Foods • Complete Proteins: • Contain all essential amino acids • Sources are animal foods with the exception of gelatin • Incomplete Proteins: • Limited in amounts or number of essential amino acids • Sources are grains, vegetables and legumes

12. Protein Sparing • Carbohydrate needed to spare protein from being used for energy • If protein is used for energy it is deaminized—nitrogen is removed—and the C, H, and O are used for energy • Low carbohydrate diets are not recommended for this reason

13. Vegetarian Diets • Vegetarianism: rely mostly on non animal foods for their diet • Levels of Vegetarianism • Lacto-vegetarians—milk only • Lacto-ova—milk and eggs • Vegans—exclude all animal products • Advantages: • Easier to maintain desired weight • Lower cholesterol and higher fiber foods • Lower rates of colon cancer and heart disease • Better digestion—low fat and high fiber

14. Vegetarian Pyramid

15. Vegetarianism cntd. • Nutritional concerns • Vitamin B12 only found in animal products • Vitamin D mainly available in milk and animal fats • Iron and Zinc are not as available in non-animal sources

16. TEST Questions • 1. Proteins are chemically different from carbohydrates and fat because they also contain: • A. Phosphorus • B. Sodium • C. Iron • D. Nitrogen

17. Test Questions • 4. The basic building blocks of protein are: • a. glucose units • b. amino acids • c. side chains • d. saturated bonds