Proteins Questions to Ponder Exam 2 Fall 2015 1 What is the structure of proteins and amino acids The amine group links with the acidic end of the next amino acid Amino acids with electrically charged side chains are attracted to H2O Amino acids with neutral side chains are repelled by water seek each other Consequently proteins have very convoluted shapes 2 What is an essential amino acid What are the nine essential amino acids Essential amino acids cannot be made by the body and therefore come from food The nine are Phenylalanine Valine Tryptophan Threonine Isoleucine Methionine Histidine Leucine Lysine 3 What are the functions of proteins in the body How much protein does the average person need Protein builds new tissues serves as enzymes hormones antibodies fluid and electrolyte balance acid base balance energy transportation and helps blood clotting The DRI recommended intake is 8 grams per kilogram of body weight 4 How proteins are digested and absorbed in the body When swallowed food arrives in the stomach acid denatures the protein strands and an enzyme cleaves amino acid strands into polypeptides and a few amino acids Enzymes from the pancreas and the small intestine split peptide strands into tripeptides dipeptides and amino acids Enzymes on the surface of the small intestine s lining and within the absorptive cells split tripeptides and dipeptides The intestinal cells absorb and transfer amino acids to the bloodstream The bloodstream transports amino acids to all the body s cells 5 What are marasmus and kwashiorkor What causes each What are the symptoms of each They are both diseases caused by protein deficiencies Marasmus is caused by chronic inadequate food intake energy vitamin mineral protein People become shriveled and lean all over Kwashiorkor is caused by sever acute malnutrition too little protein to support body functions People have swollen belies and skin rashes 6 Why might a vegetarian diet be healthier than that of a meat eater Why might it be less healthy Poorly planned meat eater s diets may lack vitamin A vitamin C folate and fiber Poorly planned vegetarian diets typically lack iron zinc calcium omega 3 fatty acids vitamin D and vitamin B12 7 What are the problems associated with protein excess Diets high in protein rich foods are associated with obesity Animal protein sources in particular can be high in saturated fat a known contributor to atherosclerosis and heart disease Animals fed experimentally high protein diets often develop enlarged kidneys or livers In humans a high protein diet worsens existing kidney problems and may accelerate a decline in only mildly impaired kidneys Evidence is mixed about whether high intakes of protein form animal sources especially when accompanied by very low calcium and low fruit vegetable intakes can accelerate adult bone loss Diets high in protein also correlate with a higher incidence of hip fractures in some populations High protein diets forces body to use proteins for energy limits overall food intake not a healthy long term diet has possible short term side effects and is not proven to be more effective than high carbohydrate diets in the long term Vitamin and Minerals 1 What is a vitamin Compare and contrast fat soluble and water soluble vitamins Vitamins are essential organic non energy yielding and micronutrients Fat soluble vitamins A D E and K are absorbed like fats first into the lymph then the blood They must travel with protein carriers in watery body fluids stored in the liver or fatty tissues They are not readily excreted tend to build up in the tissues Toxicities are likely from supplements but occur rarely from food They are needed in periodic doses because the body can draw on its stores Water soluble vitamins B and C are absorbed directly into the blood They travel freely in watery fluids most are not stored in the body They are readily excreted in the urine and toxicities are unlikely but possible with high doses from supplements They are needed in frequent doses because the body does not store most of them to any extent 2 What vitamins can be synthesized in our body Vitamin D Niacin Vitamin K and Biotin Do Not Be Katrina 3 What are the causes of vitamin deficiency syndromes beriberi pellagra and scurvy Beriberi is caused by a Thiamin deficiency Pellagra is caused by a Niacin deficiency Scurvy is caused by a Vitamin C deficiency 4 Why is vitamin A important for proper vision When light falls on retina Vitamin A splits from rhodopsin initiating a signal that conveys the sensation of sight to the brain 5 What is beta carotene Why is beta carotene important in human health Beta carotene is a strong antioxidant and serves as a Vitamin A precursor 6 What is biological function of vitamin K Synthesis of blood clotting proteins and bone proteins 7 What are free radical and an antioxidant What nutrients can act as antioxidants What is the mechanism of action of antioxidants How can antioxidants help to prevent heart disease Free radicals are molecules with unpaired electrons that cause damage to body structures B carotene Vitamin E Vitamin C Selenium Zinc and Copper act as antioxidants Antioxidants remove free radicals and protect body structures By removing free radicals antioxidants also prevent heart disease 8 What is function of folate and deficiency syndrome Folate allows normal development of the neural tube nucleic acid synthesis and amino acid metabolism Folate deficiencies cause neural tube defects anemia abnormal digestive function cancer cardiovascular disease and Alzheimer s disease 9 What is food source of vitamin B12 Tuna Swiss cheese Sirloin steak 10 What is the function of vitamin D Vitamin D mineralizes bones and teeth 11 What are major and trace minerals Major minerals are essential inorganic non energy yielding micronutrients indestructible and needed by the body in large amounts Trace minerals are also called microminerals and are needed by the body in tiny amounts 12 What are the most abundant two minerals in the body What is the significance of calcium Calcium and Phosphorus Calcium mineralizes bones and teeth causes muscle contraction and relaxation causes nerve functioning and protects against blood clotting The main thing is that it prevents osteoporosis 13 What are the dietary sources of sodium Why is high consumption of sodium harmful to health Sodium is mainly found in processed foods Too much sodium can cause high blood pressure coronary artery disease and even stroke 14
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