Chapter 6: The Proteins and Amino Acids
Chapter 6: The Proteins and Amino Acids FDNS 2100
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This 5 page Class Notes was uploaded by Jessica Lindler on Tuesday October 6, 2015. The Class Notes belongs to FDNS 2100 at University of Georgia taught by Barbara M. Grossman in Summer 2015. Since its upload, it has received 100 views. For similar materials see Human Nutrition and Food in Human Development at University of Georgia.
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Date Created: 10/06/15
Chapter 6 The Proteins and Amino Acids 1 Amino Acids Building Blocks of Protein a Proteins are sequences of amino acids AA b Types of AA 20 different amino aci Essential AA EAA Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine Essential must come from diet Nonessential can be made in body ds 9 are Essential Amino Acids Nonessential AA Alanine Arginine Asparagine Aspartic acid Cysteine Glutamic Acid Glutamine Glycine Proline Se ne Tyrosine 2 Protein Structure AA 9 Peptides 9 Polypeptides Folding Polypeptide folds into 3dimensional structure determined by AA a b Protein sequence c I ii iii iv Protein Synthesi Requires that all Sequence of AA What if an error occurs Protein denaturation Irreversible change in a protein s shape By heat acid or other agents Disrupts function Eg Heat cooking an egg or curdling of milk Acid HCl in your stomach 5 Summary essential AA available The sequence fAA in a protein is determined from a subunit of DNA determines the shape and function of the protein 0 Errors in protein synthesis may alter protein s function 0 Example sickle cell anemia Sickle Cell Anemia o Caused by error in DNA 0 Single error in AA sequence of protein hemoglobin 0 Red blood cells 0 Becomes sticky sickleshapes 0 Block arteries 0 Cells die at 1020 days normal 120 days 4 Protein Digestion 0 Protein from food becomes Amino Acids in the body 5 Functions of the Body 0 Structural and mechanical functions 0 Muscle bones teeth skin 0 Example collagen 0 Functions of body protein 0 Enzymes I Catalysts that speed up reactions in the body I May be catabolic or anabolic I Example protease o Hormones o Messenger molecules 0 Immune Function 0 Antibodies attack bacteria and viruses 0 Fluid Balance 0 Proteins attract water which allows cells to retain fluid 0 edema o Acidbase balance 0 Proteins act as buffers o Maintains pH of blood 0 Transport 0 Within the bloodstream o Membrane bound carrier 0 Source of energy 0 4 kcalgram 0 Protein and energy function I Protein is not used for energy unless 0 Little energy from other sources carb 0 Or excess protein intake I In severe calorie restriction or low carb diet the body will dismantle tissue proteins to use for energy 0 Muscle protein 9 AA 9 glucose 0 Results in muscle wasting Make sure to consume sufficient carb in order to prevent muscle wasting 6 Nitrogen balance a N Nitrogen a marker for protein b Positive Nitrogen Balance i N intake gt N output body retains N ii Eg pregnancy growth muscle building c Negative Nitrogen Balance body loses N i N intake lt N output ii Eg weight loss diet illness quotwasting disease d Zero Nitrogen Balance or equilibrium i N intake N output 7 Protein in Food a Food Group Protein I Meat ii Poultry iii Seafood iv Beans and peas v Eggs vi Processed soy products vii Nuts and seeds Protein Quality Determined by digestibility and amino acid composition Complete Protein Supplies All essential AA Animal products soy protein Incomplete Protein Low in 1 or more essential AA Most Plant Proteins Complementary Protein Combinations Grains Barley bulgar cornmeal oats pasta rice wholegrain breads Legumes Dried beans dried lentils dried peas peanuts soy products Seeds and Nuts Cashews nut butters other nuts sesame seeds sunflower seeds walnuts Vegetables Broccoli leafy greens other vegetables 8 Recommended Protein Intakes a Protein RDA i Adults 08 gkg BW b Excess protein is stored as fat c Generates ammonia NH3 to be excreted by kidneys High animal protein diets typically Are low in plant foods fiber vitamins phytochemicals Increase risk for heart disease Linked with colon cancer Stresses the kidneys Increases bone loss OOOOO Recommendation no more than 2 x RDA for protein Protein Needs for Weight Training 0 If 1 lb muscle developed through lifting o 1 lb muschle 70 H20 22 protein 7 fatash o 1b muscle454g o 22 of 454 g 100 g extra protein needed 0 100 g protein7 days 14 g proteinday o Eg1glass ofmilk8g 0 Thus no supplements required 0 If too much extra protein extra calories extra fat Protein Supplements a single AA can inhibit absorption of other AA get AA deficiency 9 Protein Deficiency ProteinEnergy Malnutrition PEM a deficiency of both protein and energy PEM is the most widespread form of malnutrition in the world Iron deficiency is the most common vitaminmineral deficiency in the world and US Consequences of PEM o Kwashiorkor 0 Older infants 13 yr 0 Not enough pro 0 Rapid onset 0 Some weight loss 0 Loss of appetite o Marasmus o Infancy lt2 yrs Not enough pro or cal Develops slowly chronic Severe muscle wearing Good appetite OOOO