The document provides an overview of proteins, including their structure, function in the body, digestion, absorption, and dietary recommendations. It discusses that the body is made up of thousands of proteins which regulate functions. Amino acids are the building blocks of proteins and there are essential and non-essential amino acids. Protein synthesis occurs through DNA instructions being carried out by the addition of amino acids with energy. The shape of a protein determines its function in the body. The document also covers protein digestion and absorption in the stomach and small intestine, as well as protein requirements in the diet.

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2. Overview of Protein Body is made up of thousands of proteins Contains nitrogen, carbon, hydrogen, and oxygen Functions Regulates and maintains body functions Provides essential form of nitrogen (in the form of amino acids)

3. Amino Acid R group Acid group Nitrogen group NH2 O R C C OH H

4. Relationship of Essential and Non-essential Amino Acids Example: Phenylalanine    tyrosine (essential non-essential) But in PKU diagnosed individuals: Phenylalanine    tyrosine (essential NOW essential)

5. Classification of Amino Acids

6. Limiting Amino Acids

7. Protein Synthesis DNA contains coded instructions Copies of codes Transferred to the cytoplasm (via mRNA) Amino acids added one at a time With aid of transfer RNA (tRNA) Requires energy

8. Protein Synthesis

9. Protein Organization Order of amino acids in a protein determines its ultimate shape Protein ’s final shape determines its function in the body

10. Protein Organization

11. Sickle Cell Anemia

12. Denaturation of Proteins Heat/acid/alkaline/enzymes Results in alteration of the protein ’s three-dimensional structure

13. Protein Denaturation

14. Protein in Foods

15. Animal Protein Contribution to our diet ~70% of our protein intake Top 5 contributors of protein in U.S. diet: Beef Poultry Milk White bread Cheese Worldwide, 35% comes from animal sources

16. Dietary Protein High-quality Complete Low-quality Incomplete All-or-none principle in protein synthesis Limiting amino acids Complementary proteins

17. Health and Plant Proteins Heart healthy Cancer-fighting Bone health Better glucose control Soy and menopausal symptoms

18. Plant Sources Provide protein, minerals, and dietary fiber Contain no cholesterol Limited saturated fats High fiber Time needed to adjust to the higher fiber load

19. Complementary Protein Food 1 Food 2 Combined CC CCCC AAAA AA CAR CAR CAR RRR RRR CAR CAR CAR

20. Complementary Proteins

21. Digestion of Protein in the Stomach Denatured By cooking and acid in the stomach Gastrin Stimulates the release of acid and pepsin Pepsin Breaks down proteins

22. Denaturation

24. Digestion of Protein in the Small Intestine Release of CCK Pancreatic enzymes: Trypsin, among others, into the duodenum Peptones  peptides  amino acids Small peptides and amino acids Ready for absorption

25. Protein Turnover Breakdown and synthesis Responds to change Amino acids can be recycled

26. Fluid Balance

27. Protein Absorption Site of digestion Microvilli surface and within absorptive cells Many different amino acid transport mechanisms Active absorption Amino acids are sent to the liver Via portal vein

28. Metabolism of Amino Acids

29. Functions of Proteins Building blocks of body components Fluid balance maintenance Acid/base balance (contribute to) Building blocks of hormones and enzymes Immune function Gluconeogenesis Energy yielding (non-preferred source) Provides highest feeling of satiety after meal

30. Protein and Muscle Production

31. RDA for Protein Promotes equilibrium 0.8 gm of protein / kg of healthy body weight 154 lb. = 70 kg 2.2 kg/lb. 70 kg x 0.8 g protein = 56 g protein kg healthy body weight

32. Protein Balance

33. RDA for Protein Increased by ~10-15 gm /day for pregnancy Endurance athletes May need 1.2 – 1.7 gm/kg healthy weight Provide about 8-10% of total kcal Most of us eat more than the RDA for protein Excess protein cannot be stored as protein

34. Is a High-Protein Diet Harmful? Low in plant foods (fiber), vitamins, phytochemicals High in saturated fat and cholesterol Excessive intake of processed red meat is linked with colon cancer Burden on the kidney May increase calcium loss in the urine Increase urine production – increase risk for dehydration

35. Malnutrition Protein-Energy Malnutrition Marasmus Seen in hospitalized patients Kwashiorkor

36. Protein Calorie Malnutrition

37. Vegetarian Diets Why become a vegetarian? Vegans Fruitarians Lactovegetarians Lactoovovegetarians Concerns for infants and children

39. Vegan Diets Complementary proteins Nutrient concerns Vitamin B12 Iron Zinc Calcium Omega-3 fatty acids