ch 6, 10-5-09

ch 6, 10-5-09 - Protein Synthesis Protein Synthesis –...

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Unformatted text preview: Protein Synthesis Protein Synthesis – Sequencing errors can cause altered proteins – Sickle­cell anemia incorrect amino acid sequence interferes with the cell’s ability to carry oxygen Protein Synthesis Protein Synthesis Sequencing errors Protein Synthesis Protein Synthesis – Nutrients and Gene Expression ­ Cells regulate gene expression to make the type of protein needed for that cell – Epigenetics nutrient’s ability to activate or silence genes without interfering with the genetic sequence. WHY DO WE NEED PROTEIN? WHY DO WE NEED PROTEIN? Vital body constituents Fluid balance Acid­base balance Immune function Glucose Energy Hormones and enzymes Roles of Proteins Roles of Proteins Building material – Growth Muscles, Blood, Skin, etc. – Maintenance Skin, GI tract, Nails, etc. Enzymes – proteins that facilitate anabolic (building up) and catabolic (breaking down) chemical reactions Roles of Proteins Roles of Proteins Roles of Proteins Roles of Proteins Hormones Hormones regulate body processes and some hormones are proteins. An example is insulin. Roles of Proteins Roles of Proteins Regulation of fluid balance Plasma proteins attract water Maintain the volume of body fluids to prevent edema which is excessive fluid – Edema: the swelling of body tissue caused by excessive amounts of fluid in the interstitial spaces; seen in protein deficiency Roles of Proteins Roles of Proteins Acid­Base Regulators Act as buffers by keeping solutions acidic or alkaline Acids are compounds that release hydrogen ions in a solution Bases are compounds that accept hydrogen ions in a solution Roles of Proteins Transporters Carry lipids, vitamins, minerals and oxygen in the body Act as pumps in cell membranes, transferring compounds from one side of the cell membrane to the other Transport Proteins Transport Proteins Roles of Proteins Roles of Proteins Immunity – Antigens: an invading agent bacteria and viruses, that invade the body – Antibodies: proteins produced in response to invading agent – Provide immunity to fight an antigen more quickly the second time exposure occurs Roles of Proteins Roles of Proteins Source of Glucose – Gluconeogenesis Source of energy – 4 kcal/g Other roles Blood clotting by producing fibrin which forms a solid clot Vision by creating light­sensitive pigments, opsin, in the retina Protein Metabolism Protein Metabolism Protein turnover – Amino acid pool Protein turnover is the continual making and breaking down of protein. Amino acid pool is the supply of amino acids that are available. Nitrogen balance – Positive nitrogen balance – Negative nitrogen balance Protein Metabolism Protein Metabolism Using amino acids to make proteins protein needed. Using amino acids to make nonessential amino acids Cells can assemble amino acids into the Protein Metabolism Protein Metabolism Using amino acids to make other compounds – Neurotransmitters Using amino acids for energy and glucose There is no readily available storage form of protein. Breaks down tissue protein for energy if needed Protein Metabolism Protein Metabolism Deaminating Amino Acids Nitrogen­containing amino groups are removed Ammonia is released into the bloodstream Ammonia is converted into urea by the liver Kidneys filter urea out of the blood Protein Metabolism Protein Metabolism Using amino acids to make fat – When energy and protein intake exceeds needs and carbohydrate intake is adequate. High­quality proteins Contains all the essential amino acids Animal foods vs. Plant foods Reference protein – Standard against used to measure the quality of other proteins Protein Quality Protein Quality Protein Quality Protein Quality Complementary proteins can also supply all the essential amino acids Combining plant foods that together contain all the essential amino acids Used by vegetarians Protein Quality Protein Quality Digestibility – Animal vs. plant Limiting amino acid – essential amino acids that are supplied in less than the amount needed to support protein synthesis Protein­Energy Malnutrition Protein­Energy Malnutrition (PEM) Acute PEM – Caused by recent severe food restrictions. – Characterized in children by weight relative to height Chronic PEM – Caused by long­term food deprivation characterized in children by height relative to age Protein­Energy Malnutrition Protein­Energy Malnutrition (PEM) Marasmus Kwashiorkor Marasmus­kwashiorkor mix Marasmus Infancy, 6 to 18 months of age Severe deprivation or impaired absorption of protein, energy, vitamins and minerals Develops slowly; CHRONIC PEM Severe weight loss and muscle wasting, including the heart Growth <60% weight­for­age Anxiety and apathy Good appetite is possible Hair and skin problems Older infants and young children, 18 months to 2 years of age Inadequate protein intake, infections Rapid onset; ACUTE PEM Some muscle wasting, some fat retention Growth is 60­80% weight­for­age Edema and fatty liver Apathy, misery, irritability and sadness Loss of appetite Hair and skin problems Kwashiorkos Kwashiorkos Marasmus­Kwashiorkor Mix Marasmus­Kwashiorkor Mix Both malnutrition and infections Edema of kwashiorkor Wasting of marasmus Protein­Energy Malnutrition Protein­Energy Malnutrition (PEM) Infections – Dysentery: infection of GI causing diarrhea and malabsorption due to depletion of nutrients Rehabilitation Nutrition intervention must be cautious, slowly increasing protein Health Effects Health Effects Heart disease – Animal products – Increased levels of amino acids Cancer – Animal products can increase risk Adult bone loss – Osteoporosis – Increased protein diets increase calcium resorption Health Effects Health Effects Weight control – High­protein foods are often high­fat foods – Protein provides satiety Kidney disease – High protein intake increases the work of the kidneys – Restricting dietary protein may help to slow progression of disease and limit kidney stone formation Recommended Intakes Recommended Intakes RDA – 0.8 g/kg/day for a healthy adult! – 10% ­ 35% of energy intake Children will need a higher protein intake – remember positive nitrogen balance for growth RDA for Protein RDA for Protein Promotes equilibrium 0.8 gm of protein / kg of healthy body weight 154 lb. = 70 kg 2.2 kg/lb. 70 kg x 0.8 g protein = 56 g protein kg healthy body wt Recommended Intakes Recommended Intakes Daily Value – 50 g protein 10% of a 2000 kcal diet Protein in abundance – Moderation is key! RDA for Protein RDA for Protein Increased by ~10­15 gm /day for pregnancy Endurance athletes may need 1.5 ­ 2 gm/kg healthy weight About 8­10% of total kcals Most of us eat more than the RDA for protein Excess protein cannot be stored as protein Supplements Supplements Protein supplements Amino acid supplements – Protein Powders have not been found to improve athletic performance – Can limit absorption of other amino acids Whey protein Purified protein preparations increase the work of the kidneys ...
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This note was uploaded on 10/31/2009 for the course HUN 1201 taught by Professor Razsaadat during the Fall '08 term at FSU.

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