Chapter62013

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  • Figure 6-9 Enzyme Action Each enzyme facilitates a specific chemical reaction. In this diagram, an enzyme enables two compounds to make a more complex structure, but the enzyme itself remains unchanged.
  • Chapter62013

    1. 1. Protein: AminoProtein: Amino AcidsAcids Chapter 6Chapter 6
    2. 2. The ChemistThe Chemist’s View of Proteins’s View of Proteins • Atoms • Carbon, hydrogen, oxygen, nitrogen • Amino acids • Carbon • Hydrogen • Amino group • Acid group • Side group or side chain
    3. 3. The ChemistThe Chemist’s View of Proteins’s View of Proteins • More complex than carbohydrates or fats • Twenty amino acids • Different characteristics • Essential amino acids • Nonessential amino acids • Conditionally essential
    4. 4. Amino AcidsAmino Acids
    5. 5. Examples of Amino AcidsExamples of Amino Acids
    6. 6. The ChemistThe Chemist’s View of Proteins’s View of Proteins • Proteins • Peptide bonds link amino acids • Condensation reactions • Amino acid sequencing • Primary structure – chemical bonds • Secondary structure – electrical attractions • Tertiary structure – hydrophilic & hydrophobic • Quaternary structure – two or more polypeptides
    7. 7. Amino Acid Sequence ofAmino Acid Sequence of Human InsulinHuman Insulin
    8. 8. The Structure of HemoglobinThe Structure of Hemoglobin
    9. 9. The ChemistThe Chemist’s View of Proteins’s View of Proteins • Protein • Denaturation • Disruption of stability • Uncoil and lose shape • Stomach acid
    10. 10. Protein DigestionProtein Digestion • Mouth • Stomach • Hydrochloric acid denatures proteins • Pepsinogen to pepsin • Small intestine • Hydrolysis reactions • Peptidase enzymes
    11. 11. Protein Digestion in the GIProtein Digestion in the GI TractTract
    12. 12. Protein AbsorptionProtein Absorption • Transport into intestinal cells • Uses of amino acids by intestinal cells • Unused amino acids transported to liver • Enzyme digestion • Predigested proteins
    13. 13. Protein SynthesisProtein Synthesis • Uniqueness of each person • Amino acid sequences of proteins • Genes – DNA • Diet • Adequate protein • Essential amino acids
    14. 14. Protein SynthesisProtein Synthesis • DNA template to make mRNA • Transcription • mRNA carries code to ribosome • Ribosomes are protein factories • mRNA specifies sequence of amino acids • Translation • tRNA • Sequencing errors
    15. 15. Sickle Cell Compared withSickle Cell Compared with Normal Red Blood CellNormal Red Blood Cell
    16. 16. Protein SynthesisProtein Synthesis • Gene expression and protein synthesis • Capability of body cells • Protein needs • Dietary influence on gene expression • Disease development
    17. 17. Roles of ProteinsRoles of Proteins • Structural materials • Building blocks for most body structures • Collagen • Replacement of dead or damaged cells • Enzymes • Break down, build up, and transform substances • Catalysts
    18. 18. Stepped Art Enzyme Enzyme Enzyme A B BA BA New compound The separate compounds, A and B, are attracted to the enzyme’s active site, making a reaction likely. The enzyme forms a complex with A and B. The enzyme is unchanged, but A and B have formed a new compound, AB. Figure 6-9 p175
    19. 19. Roles of ProteinsRoles of Proteins • Hormones • Messenger molecules • Transported in blood to target tissues • Regulators of fluid balance • Edema • Acid-base regulators • Attract hydrogen ions • Transporters – specificity
    20. 20. Examples of Hormones andExamples of Hormones and Their ActionsTheir Actions
    21. 21. An Example of TransportAn Example of Transport ProteinProtein
    22. 22. Roles of ProteinsRoles of Proteins • Antibodies • Defend body against disease • Specificity • Immunity – memory • Energy and glucose • Starvation and insufficient carbohydrate intake • Other roles
    23. 23. Preview of Protein MetabolismPreview of Protein Metabolism • Protein turnover & amino acid pool • Continual production and destruction • Amino acid pool pattern is fairly constant • Used for protein production • Used for energy – if stripped of nitrogen • Nitrogen balance • Zero nitrogen balance • Positive and negative nitrogen balance
    24. 24. Preview of Protein MetabolismPreview of Protein Metabolism • Making other compounds • Neurotransmitters • Melanin • Thyroxin • Niacin • Energy and glucose • Wasting of lean body tissue • Adequate intake of carbohydrates and fats
    25. 25. Preview of Protein MetabolismPreview of Protein Metabolism • Making fat • Energy and protein exceed needs • Carbohydrate intake is adequate • Can contribute to weight gain • Deaminating amino acids • Stripped of nitrogen-containing amino group • Ammonia • Keto acid
    26. 26. Preview of Protein MetabolismPreview of Protein Metabolism • Make proteins & nonessential amino acids • Breakdown of proteins • Keto-acids • Liver cells and nonessential amino acids • Converting ammonia to urea • Liver – ammonia and carbon dioxide • Dietary protein
    27. 27. Transamination and SynthesisTransamination and Synthesis of a Nonessential Amino Acidof a Nonessential Amino Acid
    28. 28. Urea SynthesisUrea Synthesis
    29. 29. Preview of Protein MetabolismPreview of Protein Metabolism • Excreting urea • Liver releases urea into blood • Kidneys filter urea out of blood • Liver disease • Kidney disease • Protein intake and urea production • Water consumption
    30. 30. Urea ExcretionUrea Excretion
    31. 31. Protein Functions in the BodyProtein Functions in the Body
    32. 32. Protein QualityProtein Quality • Two factors • Digestibility • Other foods consumed • Animal versus plant proteins • Amino acid composition • Essential amino acid consumption • Nitrogen-containing amino groups • Limiting amino acid
    33. 33. Protein QualityProtein Quality • Reference protein • Preschool-age children • High-quality proteins • Animal proteins • Plant proteins • Complementary proteins • Low-quality proteins combined to provide adequate levels of essential amino acids
    34. 34. Complementary ProteinsComplementary Proteins
    35. 35. Health Effects of ProteinHealth Effects of Protein • Protein deficiency • Consequences • Protein-energy malnutrition • Marasmus and kwashiorkor • Heart disease • Animal-protein intake • Homocysteine levels • Arginine levels
    36. 36. Health Effects of ProteinHealth Effects of Protein • Cancer • Protein-rich foods; not protein content of diet • Osteoporosis • Increase in calcium excretion • Animal proteins • Weight control • Kidney disease • Acceleration of kidney deterioration
    37. 37. Recommended Intakes ofRecommended Intakes of ProteinProtein • Need for dietary protein • Source of essential amino acids • Practical source of nitrogen • 10 to 35 percent of daily energy intake • RDA • Adults = 0.8 grams / kg of body weight / day • Groups with higher recommended intakes • Assumptions • Adequate energy
    38. 38. From Guidelines to GroceriesFrom Guidelines to Groceries • Protein foods • One ounce equals 7 grams of protein • USDA Food Patterns • Recommended sources • Milk and milk products • Fruits, vegetables, and grains • Read food labels • Current US and Canada intakes • Moderation
    39. 39. Protein and Amino AcidProtein and Amino Acid SupplementsSupplements • Protein powders • Muscle work vs. protein supplements • Athletic performance • Whey protein • Impact on kidneys • Amino acid supplements • Potential risks associated with intake • Lysine & tryptophan

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