© 2006 Thomson-Wadsworth Protein: Amino Acids. © 2006 Thomson-Wadsworth Amino Acids.

© 2006 Thomson-Wadsworth

Protein: Amino Acids


Amino Acids


Amino Acids

• Nonessential amino acids– a.k.a dispensable amino acids

• Essential amino acids– a.k.a indispensable amino acids

• Conditionally essential amino acids



An Essential Amino Acid


Nonessential Amino Acids


Proteins

• Peptide bond


Proteins

• Dipeptide


Proteins

• Tripeptide


Proteins

• Polypeptide


Proteins

• Amino acid sequences


• Protein shape and function


Proteins

• Protein denaturation


Protein Digestion

• Stomach– HCl– Pepsinogen pepsin

•Proenzyme


Protein Digestion

• Small intestine– Proteases

•Intestinal and pancreatic– Peptidases



Protein Absorption

• Carriers

• Capillaries

• Absorption misconceptions– Enzyme/amino acid supplements


Protein Synthesis

• Delivering the instructions– DNA

•mRNA


Protein Synthesis


Protein Synthesis


Protein Synthesis


Protein Synthesis

• Sequencing errors



Protein Synthesis

• Nutrients and gene expression


Roles of Proteins

• Building material– Growth– Maintenance


Roles of Proteins

• Enzymes


Roles of Proteins

• Hormones


Roles of Proteins

• Regulation of fluid balance– Edema

• Acid-base regulation– Acidosis– Alkalosis


• Transport proteins


Roles of Proteins

• Immunity– Antibodies– Antigens


Roles of Proteins

• Source of energy

• Other roles


Protein Metabolism

• Protein turnover– Amino acid pool

• Nitrogen balance– Positive nitrogen balance– Negative nitrogen balance


Protein Metabolism

• Using amino acids to make proteins

• Using amino acids to make nonessential amino acids


Protein Metabolism

• Using amino acids to make other compounds– Neurotransmitters

• Using amino acids for energy and glucose


Protein Metabolism

• Deamination

• Using amino acids to make fat


Protein Quality

• High-quality proteins

• Digestibility– Animal vs. plant

• Amino acid composition– Limiting amino acid


Protein Quality

• Reference protein

• Complementary proteins


Protein Quality

• PDCAAS– Protein

digestibility-corrected amino acid score


Food Labels

• Quantity of protein

• Daily Value– 50 g protein

•10% of a 2000 kcal diet


Protein-Energy Malnutrition (PEM)

• Acute PEM

• Chronic PEM



• Marasmus

• Kwashiorkor

• Marasmus-kwashiorkor mix





• Infections– Dysentery

• Rehabilitation


Health Effects

• Heart disease

• Cancer

• Adult bone loss– osteoporosis


Health Effects

• Weight control

• Kidney disease


Recommended Intakes

• RDA– 0.8 g/kg/day– 10% - 35% of energy intake


Recommended Intakes

• Adequate intake

• Protein in abundance


Supplements

• Protein supplements

• Amino acid supplements


Vegetarian Diets


Vegetarian Diets

• Health benefits


Vegetarian Diets

• Diet planning– Protein

•Lacto-ovo-vegetarians•Meat replacements

–Texturized vegetable protein


Vegetarian Diets

• Vitamins and minerals– Lactovegetarians– Vegans


Vegetarian Diets

• Omega-3 fatty acids


Vegetarian Diets

• Vegetarian diets through the life span– Pregnancy and lactation– Infancy– Childhood and adolescence


Vegetarian Diets

• Healthy food choices– Macrobiotic diets

© 2006 Thomson-Wadsworth Protein: Amino Acids. © 2006 Thomson-Wadsworth Amino Acids.

Documents

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