Protein: Amino Acids

1. Protein: Amino Acids Amino acids: building blocks of protein Copyright 2005 Wadsworth Group, a division of Thomson Learning

2. Amino Acids • Proteins: compounds composed of C, O, N, H atoms • Arranged into amino acids linked in a chain. Copyright 2005 Wadsworth Group, a division of Thomson Learning

3. Amino Acids • Nonessential amino acids • a.k.a dispensable amino acids • Essential amino acids • a.k.a indispensable amino acids • Conditionally essential amino acids Copyright 2005 Wadsworth Group, a division of Thomson Learning

5. Extra Credit • Which amino acid is not essential for adults, but is essential for infants?

6. Proteins • Peptide bond • Unites each amino acid to the next • Connects the acid end of one aa to the amino end of another aa.

7. Proteins • Dipeptide – two amino acids bonded together Copyright 2005 Wadsworth Group, a division of Thomson Learning

8. Proteins • Tripeptide – three amino acids bonded together.

9. Proteins • Polypeptide Copyright 2005 Wadsworth Group, a division of Thomson Learning

10. Proteins • Amino acid sequences • Series of amino acids bonded together to make protein • Amino acids = letters of the alphabet • Proteins = words Copyright 2005 Wadsworth Group, a division of Thomson Learning

11. Protein Review • Proteins are made from… • Amino acids • Two amino acids bonded together… • Dipeptide (for example: val-arg) • The bond that link amino acids together • Peptide bond

12. What gives protein its shape and function? • Amino acid sequence

13. Protein shape and function • Amino acids sequence gives protein its shape and function Copyright 2005 Wadsworth Group, a division of Thomson Learning

14. Proteins • Protein denaturation • Uncoil and lose their shapes and loses its functions • Example: • Heat • Acid Copyright 2005 Wadsworth Group, a division of Thomson Learning

15. Protein Digestion • Stomach • HCl = uncoils, so enzymes can attack peptide bonds • Pepsinogen (proenzyme)  pepsin (active) • HCl activates pepsinogen in the stomach • Pepsin cleaves large polypeptides  smaller polypeptides and some amino acids. Copyright 2005 Wadsworth Group, a division of Thomson Learning

16. Protein Digestion • Small intestine • Proteases • Intestinal and pancreatic • Hydrolyze to tripeptides, dipeptides, and amino acids • Peptidases • On membranes of intestinal cells split most dipeptides & tripeptides into amino acids ***Prepared and ready for absorption Copyright 2005 Wadsworth Group, a division of Thomson Learning

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18. Protein Digestion in the GI Tract

19. Protein Absorption • Carriers – transport into intestinal cells and be used • Capillaries – transport to liver • Absorption misconceptions • Enzyme/amino acid supplements Copyright 2005 Wadsworth Group, a division of Thomson Learning

20. Roles of Proteins • Building material • Growth: build bone • Maintenance: replacement, ie. dead skin cells, hair, fingernails. Copyright 2005 Wadsworth Group, a division of Thomson Learning

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22. Roles of Proteins • Proteins act as enzymes and hormones Copyright 2005 Wadsworth Group, a division of Thomson Learning

23. Roles of Proteins • Regulation of fluid balance • Acid-base regulation • Transporters for nutrients • Hemoglobin carries Fe Copyright 2005 Wadsworth Group, a division of Thomson Learning

24. MWF

25. Roles of Proteins • Immunity • Antibodies (proteins) • Antigens (invaders) Copyright 2005 Wadsworth Group, a division of Thomson Learning

26. Roles of Proteins • Source of energy • Other roles • 3 general functions: • Maintenance & Growth • Regulatory • Energy Copyright 2005 Wadsworth Group, a division of Thomson Learning

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28. Protein Metabolism • Protein turnover: process in which or body continually make and breakdown proteins. • Amino acid pool Copyright 2005 Wadsworth Group, a division of Thomson Learning

29. Protein Metabolism • Using amino acids to make proteins • Using amino acids to make nonessential amino acids Copyright 2005 Wadsworth Group, a division of Thomson Learning

31. MWF

32. Protein Metabolism • Using amino acids to make other compounds • Neurotransmitters • Tyrosine  epinephrine, nor- • Using amino acids for energy and glucose Copyright 2005 Wadsworth Group, a division of Thomson Learning

33. Protein Metabolism • Deamination: N are stripped when aa are broken down • Ammonia  liver  urea  kidneys • Using amino acids to make fat Copyright 2005 Wadsworth Group, a division of Thomson Learning

34. Protein Quality • High-quality proteins • Digestibility • Animal vs. plant • Amino acid composition • Limiting amino acid Copyright 2005 Wadsworth Group, a division of Thomson Learning

35. Protein Quality • Reference protein • How protein vs. requirement • Complementary proteins Copyright 2005 Wadsworth Group, a division of Thomson Learning

36. Protein Quality • PDCAAS • Protein digestibility-corrected amino acid score Copyright 2005 Wadsworth Group, a division of Thomson Learning

37. Protein-Energy Malnutrition (PEM) • Acute PEM • Chronic PEM Copyright 2005 Wadsworth Group, a division of Thomson Learning

38. Protein-Energy Malnutrition (PEM) • Marasmus • Kwashiorkor • Marasmus-kwashiorkor mix Copyright 2005 Wadsworth Group, a division of Thomson Learning

39. Marasmus Copyright 2005 Wadsworth Group, a division of Thomson Learning

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41. Protein-Energy Malnutrition (PEM) • Infections • Dysentery; infection of GI tract • Rehabilitation Copyright 2005 Wadsworth Group, a division of Thomson Learning

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43. Health Effects • Heart disease • Cancer • Adult bone loss • osteoporosis Copyright 2005 Wadsworth Group, a division of Thomson Learning

44. Health Effects • Weight control • Kidney disease Copyright 2005 Wadsworth Group, a division of Thomson Learning

45. Recommended Intakes • RDA • 0.8 g/kg/day • 10% - 35% of energy intake Copyright 2005 Wadsworth Group, a division of Thomson Learning

46. Recommended Intakes • Adequate intake • Protein in abundance Copyright 2005 Wadsworth Group, a division of Thomson Learning

47. Supplements • Protein supplements • Digestibility • Athletes • Initial body building • Amino acid supplements • May cause an imbalance of other amino acids Copyright 2005 Wadsworth Group, a division of Thomson Learning

48. Protein Synthesis • Sequencing errors Copyright 2005 Wadsworth Group, a division of Thomson Learning

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50. Vegetarian Diets Copyright 2005 Wadsworth Group, a division of Thomson Learning