Unit 3 - Lecture notes 9-12 PDF

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Mark Kern ...

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Proteins Definition and structure ● Organized complex of amino acids ● Primary structure: sequence of amino acids ● Secondary structure: sequence of amino acids are linked by hydrogen bonds ○ Pleated sheet ○ Alpha helix ● Tertiary structure: certain attractions are present between alpha helices and pleated sheets ● Quaternary structure: 2 or more proteins join together Amino acid structure ● C, H, O, N (sometimes S) ● Amino acid + acid group ● Amino acids vary by side chain (residue) Protein structure ● Complex chain of amino acids ● Dipeptide: 2 amino acid chain ● Tripeptide: 3 amino acid chain ● Polypeptide: usually many amino acids ● Protein: 50 (or 100) or more amino acids ● Peptide bond: a molecule of water is removed from two glycine amino acids to form a peptide bond Amino acid classifications ● Essential amino acids: can get from diet, body can also make them ● Non essential amino acids ● PVT MT HILL

Protein classification ● Complete- foods that supply all essential amino acids we need ○ Fish, beef, chicken ● Incomplete- contain protein but dont provide all 9 essential amino acids needed ○ Plants

Protein sources

Legumes ● Soybeans especially high quality ○ Only plant complete protein Nuts ● Not a complete source of protein Protein complementation ● Combining foods with incomplete proteins to provide adequate amounts of all essential amino acids ○ I.e. beans and rice ● Probably not necessary within a meal Proteins Requirements ● Adult RDA: 0.8 g/kg ● Per weight, need is greatest with infants ● Protein: usually recommended 12-15% of calories ○ AMDR is 10-35% of calories ● Athletes likely to need more than RDA Protein types ● Enzymes ● Hormones ● Structural proteins ● Transport proteins ● Immunoproteins Metabolism ● Digestion and absorption ○ Digestions of proteins begins in stomach ○ Digestion continues in small intestine ○ Amino acids, dipeptides and tripeptides are absorbed ○ Amino acids transported to liver

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Liver synthesizes amino acids and proteins or sends amino acids to bloodstream

Metabolic fates of amino acids ● Body cells synthesize proteins, creatine, etc ● Nitrogen forms waste products (urea) eliminated mainly by kidney ● Carbon skeleton of amino acids used for fat or carbohydrate production

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Protein synthesis ● Genes determine the sequence of amino acids in each protein ● Genetic information in a cell goes from DNA -> RNA -> protein Vegetarianism ● Lacto-ovo vegetarian: includes dairy products, eggs, vegetables, grains, legumes, fruits, and nuts, excludes flesh and seafood ● Lacto- vegetarian: includes dairy products, vegetables, grains, legumes, fruits, and nuts Protein deficiency ● Protein energy malnutrition (PEM) is most widespread form of malnutrition in world today ● 2 major forms ○ Marasmus: severe chronic malnutrition, fat and muscle depleted ○ Kwashiorkor: malnutrition with edema (ascites)- fluid accumulates in abdomen Excess protein ● Not a major acute concern ○ Unless kidney problems or certain other conditions ● Usually associated with high intake of saturated fat and cholesterol ● May promote bone loss

What will he say next?

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Coconut oil- tropical fat Mostly saturated fat Long chain fatty acid Lard healthier than coconut oil

Lipids Major types ● Triglycerides (fat) ● Cholesterol ● Phospholipids Triglycerides ● Glycerol + 3 fatty acids ● > 95% of dietary lipid ● Carboxylic acid: alpha end ● Methyl: omega end ● Chain length varies ○ Short chain: less than 6 carbon ○ Medium chain: 6-10 carbon ○ Long chain: 12+ carbon ● Degree of saturation ○ Saturated: all carbons have H ○ Monounsaturated: 1 double bond ○ Polyunsaturated: 2+ double bond ● Type of double bond varies ○ Cis: same, hydrogens are on same sides of fatty acid backbone ■ Kinks fatty acid, changes properties ○ Trans: across, hydrogens are on opposite sides of fatty acid backbone ■ Keeps fatty acid straight ● Location of double bond varies ○ Omega 3 ○ Omega 6 ○ Omega 9 ● Essential vs. non-essential ○ Linoleic acid- omega 6 (essential) ○ Alpha- linolenic acid- omega 3 (essential) ● EFA deficiency symptoms ○ Reproductive failure ○ Skin abnormalities ○ Kidney and liver disorders ○ Growth and vision impairment in infants ● Body stores essential fatty acids --> extreme deficiencies are rare ● Adequate intakes

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Linoleic acid ■ 12 g/day females ■ 17 g/day males ○ Linolenic acid ■ 1.1 g/day females ■ 1.6 g/day males ● AMDRs ○ Linoleic acid ■ 5-10% of kcal ○ Linolenic acid ■ 0.6-1.2% of kcal ● Glycerol ○ Not lipid soluble ○ Can be produced in CHO metabolism ○ Can be converted to CHO through gluconeogenesis Cholesterol ● Manufactured in animals ● Not found naturally in plant products (animal products only) ● Found in foods prepared with animal products ● Your body needs cholesterol Phospholipids ● Most are similar to triglycerides except one fatty acid is replaced with a phosphate group ● Function as part of cell membranes and specific metabolic processes ● Make up cell membranes Fat digestion ● Little in mouth or stomach ● Small intestine ● Intestinal lining ○ Absorbed by intestinal villi ○ Small short chain fatty acids small enough to directly enter blood stream...