nutri sci notes part 2

nutri sci notes part 2 - NutriSciExam2 Protein...

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Nutri Sci Exam 2 20:08 Protein - composed of amino acids (AA) - 20 AA in nature - AAs – C, H, O, N sometimes S-N distinguishes protein - AA joined by peptide bonds to make peptides - peptides - short chains of AA - insulin – 51 AA - proteins - hundreds of thousands of AA - sequence carried by DNA  -one gene   one protein - shape determines chemistry - digestion of proteins - stomach acid denatures protein - protease in stomach and small intestine break proteins into single AA - protein functions body constituents blood clotting proteins blood transport proteins
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lipo proteins - structural components muscle organ tissue connective tissue bone matrix cell membrane - maintain fluid balance attracts and retains fluids in the blood through osmosis edema (accumulation of fluid under the skin determined by balance of fluid  homeostasis) acid/base balance blood proteins buffer - regulation most proteins are enzymes enzymes control chemical reactions some hormones are peptides   body-wide effect neurotransmitters 3 AA are neurotransmitters or precursors - immune system foreign proteins –antigens antibodies (protein) attack antigens
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protein deficiency decreases immune response - energy proteins supply about 10% of total energy needs brain uses glucose gluconeogenesis: create glucose from certain AA glucose can only be made from protein (not fat) protein supplies 4 kcal/gram - protein requirement  RDAs based on age and body weight adults about 0.8g/kg body weight/day avg. weight female should get 44g/day avg. weight male should get 63g/day growing children should get 9.2g/kg body weight/day athletes up to 1.5g/kg body weight/day protein needs met by <1200 kcals of typical diet adequate calories   adequate protein - excess protein used for energy strip nitrogen; excreted in urine weakens bones  draws calcium out kidney stones
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low bone density - average intake males: 90 g/day females: 70 g/day - protein energy malnutrition (PEM) rarely find protein deficiency alone usually energy deficient as well edema, emaciation  starvation Marasmus: muscle wasting, reduce work capacity, sick, emaciation (loosing body fat  and muscle) Kwashovkor: same thing happens plus abdominal edema (fluid accumulation) - protein quality essential AA (9) can’t be synthesized by body must eat them complete protein contains all 9 EAAs - biological value limiting AA stops protein synthesis BV = N retained/N consumed More N retained, better quality of the protein chemical score = % utilized
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- eggs=100; milk=93; fish=76; beef=74; soy beans=73; whole wheat=65; peas=64;  peanuts=63; gelatin=11 - animal proteins meat, fish, poultry, eggs, milk
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nutri sci notes part 2 - NutriSciExam2 Protein...

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