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Proteins 1 How is the chemical structure of protein different and similar to that of complex carbohydrates Ex they are both long chains of building block units How is the chemical structure of a monosaccharide different from that of an amino acid just in general terms Chpt 6 and Lesson 4 A protein is made of long chains of amino acids linked together by peptide bonds Complex carbohydrates are made of glucose units in straight or branched chains A monosachharide contains one sugar unit Proteins contain nitrogen in the form of an amino acid same basic structure with characteristics determined by a side R group 2 Matt just ate his quarter pounder for lunch Briefly outline the process of digestion and absorption of beef protein 1 Starts in mouth chewing 2 Stomach HCL denature proteins pepsin is activated to further break down proteins to smaller 3 Small intestine 90 of digestion of proteins occurs here pancreatic enzymes break polypeptides polypeptides down further to amino acids 4 Absorbed by active transport travels to the portal vein and then to the liver 3 What does it mean that an amino acid is a precursor molecule List four functions of some of the essential amino acids as precursors to other molecules other than their use in protein synthesis Precursor molecule is the starting point for other molecules 4 functions of essential amino acids other than protein synthesis 1 Act as precursors ex tryptophan can be converted to serotonin 2 Used for fuel but to lesser degree than fatty acids and glucose 3 Converted to fatty acids and put into fat cell storage when energy in is greater than energy out there is too much protein being converted to fat 4 Carbon portion can be converted to glucose in a process called gluconeogenesis which happens in starvation in Lesson 4 4 Amino acids build a variety of proteins in the body Briefly describe the roles of proteins as outlined 1 Collagen the framework for bone teeth structures 2 Regulate fluid balance R groups are charged and can attract water 3 Maintain acid base balance 4 Transport nutrients to cells Immunity antibodies are proteins 5 6 Hormones insulin and gastrin are protein hormones 7 Catalyze reactions 8 Transporters 5 For amino acids what is deamination What happens to the ammonia and urea as an end product of this process Chpt 6 Deamination amino acids are stripped of their nitrogen containing amino groups first step when amino acids are broken down Products of deamination are ammonia and a keto acid the carbon part of the amino acids Ammonia combines with CO2 and is excreted as urea 6 List the four essential amino acids shown in lesson 4 page 2 How many essential amino acids are in the diet Describe the sources of amino acids for the amino acid pool Why must this amino acid pool be fairly balanced from day to day 4 essential amino acids Phenylalanine methionine tryptophan lysine There are 9 essential amino acids in diet 3 Sources of amino acids for the pool the diet produced from degradation of proteins in cells synthesized from organic molecules in cells Must be balanced day to day because if not protein synthesis will be slowed and amino acid functions compromised 7 If you were to eat one protein food for two weeks that had one of the non essential amino acids missing what would happen Assume all other nutrients are adequate If you were to eat one protein food for two weeks that had one of the essential amino acids missing what would happen NOTE This cannot ever happen with foods only with purified diets formulated in a laboratory If you do not have essential and nonessential amino acids balanced protein synthesis is limited Essential and nonessential must always be balanced 8 What determines the quality of a protein How might you measure digestibility of a protein Which has the highest digestibility wheat protein or egg protein Protein quality is judged by digestibility and its amino acid profile how many amino acids it has Digestibility is measured based on amino acid content higher amino acid content higher quality more digestible Egg protein has higher digestibility than wheat protein 9 Identify two foods with high quality complete protein and two foods with lower quality incomplete or better described as less complete protein High contains all essential amino acids highly digestible foods meat eggs milk fish poultry about 97 digestibility Lower limiting in one or more amino acid low digestible foods legumes nuts vegetables 65 80 digestibility 10 Two corn tortillas and refried pinto beans is a lunch that exemplifies complementing proteins Explain What does limiting amino acid in a protein mean List the limiting amino acids in corn grains and legumes Limiting amino acid an essential amino acid that is present in low amounts Complimenting proteins mixing plants with different amino acids to have a balanced meal and cover all amino acids Limiting amino acids in wheat corn lysine Limiting amino acid in legumes methionine 11 Refer to Matt s diet and SuperTracker records from Lesson 1 study questions Matt eats 125 g of protein and 3360 kcalories day What percent of his kcalories are from protein Recall that protein is 4 kcal g You should know how to calculate this and not rely on the SuperTracker printouts Calculate Matt s protein RDA Use Activity 1 in Lesson 4 to guide you in this calculation Refer to the BMI table at the back of the text book to arrive at a high healthy body weight for Matt choose 177 pounds as a healthy weight for Matt Using his RDA and the Acceptable Macronutrient Distribution Range AMDR would you say that Matt is consuming inadequate protein adequate protein or way too much protein potentially harmful amounts Note You will be studying assessment of healthy weight status in a future lesson How to find his kcalories from protein Multipy 125g x 4 because there are 4 kcal g for protein 500 Divide 500 amount of kcal from protein he consumed 3360 total kcal for the day 14 88 Answer 14 88 of his kcal are from protein How to find his protein RDA First convert lbs to kg by dividing weight by 2 2 177lbs 2 2 80 5 Then multiply weight in kg by 8 80 5 x 8 64 4 grams know how to calculate kcal and RDA Since he eats 125g of protein he is above recommendations and should cut back 12 Sarah a college freshman has been gaining about 1 pound every 2 weeks during the first 3 months of college Her weight is now at 132 pound 60 kg which is still healthy for her and she eats about 96 grams of protein per day Calculate her RDA for

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PSU NUTR 251 - Proteins

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