NTR 343 Final Exam Quiz Bank 2022

NTR 343 Final Exam Quiz Bank 2022 1. All of the following B vitamins are involved in oxidative decarboxylation of pyruvate except: c. Folate 2. Explain in scientific detail how certain foods can inhibit the absorption of thiamin. List four food examples. Some foods contain thiaminases which break the weak methylene bridge between the two rings in the thiamin structure. Example foods are raw fish, tea, shrimp, mussels, clams, fish paste, betel nuts, ferns 3. Which of the following is not a function of thiamin? c. Synthesis of FADH2 5. What is the Tolerable Upper Level of thiamin? Why was this amount established.? There is none, as it would not occur from diet. 6. Name and explain three exceptions of vitamins that do not have to be provided for in the diet. Vitamin D: synthesized in skin by high energy radiation Vitamin K: synthesized in gut by intestinal flora Niacin: converted from tryptophan in tissues Choline: synthesized in metabolism 7. Why is milk kept in a cardboard or opaque container? Milk is kept in opaque containers because the riboflavin that is found abundantly in milk is unstable and easily destroyed when exposed to UV light 8. Explain the role of FAD in the restoration of glutathione to its active form. FAD is the coenzyme for glutathione reductase; it adds hydrogens to the oxidized form of glutathione to create the reduced form that is active. 9. A dietary staple of cornbread led to pellagra in the southern United States, yet a dietary staple of corn tortillas did not cause a deficiency in niacin. Explain the scientific reason for this. Niacin in the corn meal of cornbread is bound to a protein, so the vitamin is not available. Corn tortillas are made from corn meal that has subject to alkaline hydrolysis (cooking in lime water or CaOH) to make masa harina (the ingredient for tortillas). This process liberates the niacin (and creates the ability to make a tortilla from meal that sticks together). 11. What are the differences between the functions of NAD and NADP? Be specific NAD is needed for energy metabolism (Including glycolysis, oxidative decarboxylation of pyruvate, oxidation of acetyl CoA, beta oxidation of fatty acids, and oxidation of ethanol) while NADP is needed for synthesis of fats, cholesterol, and steroid synthesis. 12. Explain why B6 supplements can cause toxicity. How does this compare to Vitamin B12? B6 supplements are in the form of pyridoxine, which is a competitive inhibitor of the active enzyme, pyridoxal phosphate. Additionally, an excess of B6 and a deficiency of Vitamin B12, can both cause neuropathy. 13. Explain the function of Delta-6-Desaturase and how it is related to a B vitamin. It is a PLP-dependent enzyme that metabolizes both omega 6 and omega 3 fatty acids to 20 carbon compounds by desaturation of linolenic and gamma-linolenic acid. 14. List three food sources of Vitamin B6 . Is it present in enriched flour? Explain why or why not. Meat, Poultry, Fish, and Starchy Vegetables. It is not in enriched flour because it is found in many foods and requirements can be reached within an adequate diet. 15. List four inhibitors of the digestion of folate alcohol, acidic environment, cabbage, zinc deficiency, legumes, oranges pick four 16. Name and explain the role of micronutrients required for folate digestion and activation. Zinc is required for digestion as it shortens the polyglutamate tail of folate from foods to form the monoglutamate form that can be absorbed. Vitamin B12 is required for activation; folate is inactive in its methylated form, and B12 is used to remove the methyl group. 17. Explain the dual role of folate in cancer development. How is this related to the tolerable upper limit? Low folate intake protects against early carcinogenesis. But high folate intake can promote advanced carcinogenesis. High levels of folate (1000 mg/d) increased the risk of advanced colorectal lesions; so the upper limit is 1000 mg (1 mg). 18. Where was folate given as a supplement by the Public Health Service in the United States? Why? The Rio Grande Valley. This area has had a high incidence of neural tube defects. Although it could have a multifactorial etiology, this may have been a consequence of folate deficiency in some pregnant women. 19. What age group is most likely to have a vitamin B12 deficiency and why? The elderly (>50 years) because they secrete less acid and less intrinsic factor and may have used proton pump inhibitors that reduce acid secretion for >2 yrs. 20. Why is vitamin B12 deficiency almost nonexistent among vegans in third world countries than vegans in developed countries? The sanitation process of root vegetables sold in third world countries does not fully remove the dirt from all the vegetables, and the dirt has fecal material which contains bacteria that produce vitamin B12. 21. Explain how choline can contribute to the prevention of cardiovascular disease. Choline can be oxidized to betaine in the liver. Betaine can then function as a methyl group donor to homocysteine by the action of a methyltransferase enzyme generating methionine. Reduction of homocysteine levels lowers the risk for health disease and stroke. 22. A patient is suspected to have a choline toxicity. What would the symptoms, and likely be the cause of the toxicity? The patient may have a fishy body odor, vomiting, salivation, sweating, decreased blood pressure, or tinnitus. Deficiency would likely be due to use of supplements. 23. Why is choline a "conditionally essential" vitamin? Humans are capable of producing choline from glycine. Yet there is an RDI for choline because it is important for fetal development during pregnancy. 25. Describe the functions of the three biotin-dependent carboxylases. Explain how each product affects metabolism. Pyruvate carboxylase converts pyruvate to oxaloacetate. Oxalacetate will enter the TCA cycle if ATP is needed; otherwise, it can participate in gluconeogenesis. Acetyl CoA Carboxylase forms malonyl CoA from acetate. This is the first step in fatty acid synthesis (lipogenesis). Propionyl Co-A carboxylase converts Propionyl-CoA to methylmalonyl-CoA. Methylmalonyl-CoA can be converted into succinyl Co for the TCA cycle. This enables metabolism of odd chain fatty acids. 26. How does biotin affect gene expression? How prevalent is this effect? Biotin binds to histones (proteins that package DNA); thus, altering DNA replication and transcription. >2000 genes use biotin for expression of cell signaling & cell cycle. 27. Why would consumers of raw eggs, but not cooked eggs, have the potential to become biotin deficient? In raw egg whites, the protein avidin is able to tightly bind biotin, thus preventing its absorption in the small intestine. However, when egg whites are cooked, this process denatures the avidin and prevents its binding to biotin, allowing for absorption. 8 - 11 eggs/day 28. What are the three major symptoms of biotin deficiency? Alopecia, inflammation of the eyelids, and nervous problems 29. Pantothenic Acid deficiency presents differently in various animal species. Name 3 ways deficiency presents in animals. Dermatitis in chicks, grey hair in rats, goose stepping in pigs, and anemia in ducks 30. List three reasons for an increased need of pantothenic acid. Describe the reasons why for each reason. Alcoholism (low intake), diabetes (increased excretion), inflammatory bowel disease (impaired absorption). 31. Why are the symptoms of pantothenic acid deficiency vague? What is the best known symptom? Because pantothenic acid deficiency is usually accompanied with other nutrient deficiencies. It is difficult to isolate and determine the symptoms related specifically to pantothenic acid. Burning foot syndrome. 32. What are the functions of coenzyme A, with regard to carbohydrate metabolism? oxidative decarboxylation of pyruvate oxidative decarboxylation of alpha-ketoglutarate 33. What populations are most at risk for Vitamin C deficiency? What is the amount of body stores at which symptoms appear? Populations most at ri Populations most at risk are - smokers, infants fed with evaporated or boiled milk, elderly (taking salicylates), those with low socio-economic status, (less access to fresh fruits & vegetables), malabsorption or cancer; 300 mg Vitamin C 34. What amount of vitamin C is needed to double iron absorption? What is an alternative way to increase absorption as well? 25 mg of vitamin C. 1 gram of meat tissue has the same effect as 1 mg Vitamin C. 35. Explain how vitamin C plays a role in carnitine synthesis. Give the role of carnitine and consequences of a deficiency Vitamin C reduces iron to regenerate it as a cofactor for enzymes involved in carnitine synthesis. Carnitine carries fatty acids into the mitochondria where they are oxidized to produce energy. With a deficiency, an individual will feel fatigue due to a lack of energy produced (ATP). 37. Explain the role of Vitamin C in collagen formation. Why is this important? (0.42 pt) Vitamin C participates in collagen synthesis by hydroxylation of lysine and proline to cross-link its three polypeptide chains. This winding of the chains around each other increases strength and rigidity of the skin, and make healthy connective tissue. Collagen is about 1/3 of body protein. 38. List five symptoms of scurvy, beginning with the earliest to appear. What is the current DRI for vitamin C in adults? How does this match the minimum amount needed to prevent scurvy? Explain. Symptoms of scurvy include: fatigue and weakness; red skin discoloration due to blood under the skin, impaired wound healing, joint pain, hyperkeratosis, diarrhea, , gum inflammation, lung and/or kidney problems (pick 5). The current DRI is 90 mg/d for men and 75 for women. This is much higher than the 10 mg needed to prevent scurvy. But the higher amount is recommended to promote optimal health. 39. Explain the different methods of absorption for the active and inactive form of vitamin C. (0.45 pt) Ascorbic acid, the reduced, active form, is absorbed into the cell via a sodium-dependent transporter (SVCT). The oxidized, inactive form, dehydroascorbic acid, is absorbed via glucose transporters (GLUT1 and GLUT3). It is then reduced to active ascorbic acid in the cell by glutathione. 40. Why do humans need Vitamin C through dietary sources, while other species do not? Name other species which also have a Vitamin C requirement. Humans cannot synthesize the enzyme gulonolactone oxidase, which is required to synthesize vitamin C. Because humans do not have this required step, vitamin C must be consumed from other sources, either through food or supplementation. Guinea pigs, new world monkeys, channel catfish. 41. Explain the scientific basis of the "Five-A-Day health campaign used in the past to promote good nutrition. This refers to five servings a day of fruits and vegetables in the diet. This amount matches the maximum amount of vitamin C that can usually be absorbed - 200 mg. Ingestion of amounts over this are not absorbed and wasted. 42. Describe how both a deficiency and excess of Vitamin A can affect bone development. In a deficiency, it reduces the deposition by osteoblasts and reduces breakdown by osteoclasts which impairs bone breakdown and causes bone overgrowth. In excess, it will inhibit osteoblasts and activate osteoclasts, which will increase fractures. 43. Compare and contrast the functions of the three forms of Vitamin A. Both retinol and retinal, which can be converted to and from one another, participate in vision, sexual reproduction (in rats), bone health, and immune function. Retinoic acid is irreversibly converted from retinal and is an excretion product; its functions include cell differentiation, bone and skin health and immune function 44. Why would a dermatologist advise their patients starting Accutane not to plan on becoming pregnant and to have two specific forms of birth control, as well as a negative pregnancy test? Accutane is a retinoid (13-cis retinoic acid), and administration of accutane is at least 2.5 mg of daily Vitamin A intake; Accutane is teratogenic and can cause birth defects at 6X the RDA. 45. What fat-soluble vitamins interact with vitamin A, and how are these affected? Excess vitamin A can interfere with vitamin K absorption, and high levels of b-carotene can decrease plasma vitamin E. 46. List five signs/symptoms of Vitamin A toxicity. -Nausea, vomiting, blurred vision, increased intercranial pressure, dizziness, diarrhea, skin peeling, and muscle incoordination 47. What function does vitamin A have in mucous secretion during a cold? Vitamin A maintains healthy goblet cells that secrete mucous. In a cold the mucus is increased, so that the lysozymes in the mucous can degrade foreign bacteria and viruses. 47. What are the three possibilities for retinoic acid in the liver cell? It can go to the nucleus to affect gene expression; be conjugated with glucuronic acid to form bile and excreted; or form 4 oxyretinoic acid which combines with retinol binding protein to be excreted as holo-retinol binding protein. 49. What is the most effective antioxidant of all the nutrients? How does it work? How does this differ from other antioxidants (name these)? Lycopene. It transfers energy from singlet oxygen and free radicals to quench these so they return to the ground state. It releases the energy as heat and does not need to be regenerated to be active again, as do Vitamin C and E. 50. Other than blindness, why is Vitamin A deficiency such a problem in young children in low-income countries of the world? It can reduce immunity, leading to greater incidence of dying from infections such as measles 51. Explain why red, yellow and orange fruits and vegetables should be included in the diet. Give specific examples of their functions and how these would affect health. These contain carotenoids that function as antioxidants for eye health and prevention of cardiovascular disease, as well as cell proliferation and growth, and immune response. 52. Would you recommend that someone take β-carotene for lung cancer or having been exposed to asbestos? No, increases mortality 54. Why are the elderly at greater risk for vitamin D deficiency? What are the RDIs for elderly and young adults? Elderly drink little milk, often do not go outside in the sun, and may lose their ability to hydroxylate the active form of Vitamin D due to decreased kidney and liver function. The RDI is 20 and 15 ug/day, for elderly and young adults, respectively. 55. Why is it not possible to develop vitamin D toxicity from the sun? The byproducts lumisterol and tachysterol are formed in metabolism. Vitamin D binding protein has a low affinity for these byproducts, and they are prevented from circulating within the body and sloughed off with the skin. 56. How might Vitamin D be related to treatment of COVID-19? Helps prevent autoimmune disorders by downregulating inflammatory cytokines 57. Explain the mechanism by which active vitamin D is excreted. calcitriol is hydroxylated at the 24 carbon position, subsequent reactions create calcitroic acid- which is then excreted, mainly via bile in the feces. 58. List five specific possible causes of a Vitamin D deficiency. Of these, what are the most recent and significant possibilities for the world? Insufficient exposure to the sun by use of sunscreen (reduced by 99% from SPF 15); women in purdah, air pollution, minimal exposure of infants, or multiple pregnancies, breastfeeding with supplementation, low vitamin D in diet, kidney or liver disorders, and anticonvulsant drug therapy. (Pick 5) Use of sunscreen and air pollution. 59. Which of the following does Vitamin D NOT do? e. All of the above are not true 60. What percentage of vitamin K is produced in the gastro-intestinal tract in adults? Why is it that newborn babies need an injection at birth? What would be the consequences if this was not done? 50% is synthesized in the gastro-intestinal tract. Babies need an injection at birth because they are born with sterile GI tracts that cannot produce vitamin K. There might be internal bleeding such as cerebral hemorrhage. 61. Which of the following symptoms of vitamin E deficiency that occur in animals is not true? b. Dogs: sinus infection 62. Why is it not recommended to take Vitamin E supplements? Research findings have not shown that vitamin E helps lower the risk for heart disease. In contrast, Vitamin E supplements in a healthy population were associated with a higher risk of stroke. 63. A newborn patient is suspected of having a vitamin K toxicity. What are their symptoms and what is the likely cause of toxicity? The newborn will have hemolytic anemia, liver damage, and jaundice. The likely cause is from an overdose of synthetic K1 since there is no tolerable upper level for vitamin K from foods. 64. Name the only free-living population that has been reported to exhibit beneficial effects of Vitamin E supplementation? What are these? The elderly population has been reported to exhibit improved immunity for upper (but not lower) respiratory infections. 65. How does vitamin E prevent oxidative damage to a cell? What type of damage can occur? Once it exerts its effect, will it still be effective in the future? Vitamin E inserts itself in the phospholipid bilayer in cell membrane. As free radicals attack, electrons are removed and this can damage lipids, DNA or proteins, leading to possible cancer. But vitamin E will quench the free radicals and become a free radical itself. But Vitamin E can be regenerated from electrons from Vitamin C. 66. How is calcium from the diet transported into circulation, and how does this relate to calcium requirements and the presence of vitamin D? What happens when the calcium intake is high? Calcium enters the enterocyte through TRPV6 membrane channel proteins: it is shuttled across the enterocyte by the calbindin protein, and enters the bloodstream through the Ca2+ -ATPase pump. The expression of these transporters declines with age, so requirements increase. Vitamin D stimulates the formation of calbindin and the Ca2+ -ATPase pump. When Ca intake is high, it is shuttled between the enterocytes into the blood via passive paracellular diffusion. 67. Name three ways that calcium can be transported through the body. Calcium can be free as an ionized form - Ca2+ , bound to protein (i.e albumin), or in a compound (i.e calcium citrate) 68. What is not an important function of phosphorus in the body? E. Nerve transmission 69. What is the availability of minerals in pita bread? Explain scientifically. Pita bread is formed from whole wheat flour. This flour contains phytate, a chemical compound which contains phosphates whose oxygen molecules bind to cation minerals such as Ca2+ , Zn2+, and Mg2+. Since pita bread is unleavened, it does not undergo fermentation. During fermentation, the heat and moisture activate phytases, enzymes which break the phosphate bonds to the cation minerals so that these are now available. 70. How is alcohol consumption related to bone health? Moderate alcohol intake can increase bone mineral density, but alcohol abuse is associated with osteoporosis and bone fractures. 6. Which of the following is not found in bone: D. Selenium 71. What is calmodulin? What does it do? Give two example of its functions and its associated enzymes. It is a messenger protein that binds to Ca2+ . It acts as an enzyme regulator and in signal transduction. It stimulates/inhibits enzymes in muscle contraction, cell cycle regulation, intracellular signaling, phosphorylation, & fertilization. Specifically, it activates ATPase, phosphorylase kinase, phospholipase A2, protein kinase C, NAD kinase, pyruvate kinase (Pick 2) 72. What are the causes of calcium deficiency? What are the symptoms? Who are the individuals at risk? Causes are kidney disease, vitamin D deficiency, or diseases that inhibit PTH production. Pick 2 Symptoms are muscle spasms, convulsions (tetany), and Chvostek sign. Pick 2 Individuals at risk are those immobilized (Ca loss from bone), with fat malabsorption or with long time diuretic use (increased excretion). Pick 2 73. If you had to recommend a calcium supplement, which one would you recommend and why? Would you routinely recommend a calcium supplement - why or why not? Ca Citrate: When HCL production is low; can be ingested without food Ca Carbonate: Gastro-intestinal distress, constipation, may contain Al & lead (Pb) if from oyster shells Ca Lactate: Greater fasting absorption rate (exceeds milk) Bone meal: may contain Pb Absorption 25-40% - Increased if consumed with meal & < 500 mg 74. What is the relationship of zinc to enzymes? Name four examples and explain their function. Zinc is a constituent of ~100 enzymes. Carboxypeptidase A is involved in the digestion of the COOH end of proteins, Alcohol dehydrogenase breaks down alcohol to aldehyde, Superoxide Dismutase is involved in antioxidant defense to destroy superoxide anions, Carbonic Anhydrase is a CO2 carrier in red blood cells and kidney. Alkaline Phosphatase is necessary for skeletal development; (releases phosphate from bone & liver). Delta Amino Levulinic Acid dehydratase is a precursor for hemes, chlorophylls & vit B12. Pick 4 75. How are zinc levels affected during an infection? How does this compare to other trace elements? Plasma Zn decreases and it is sequestered by the liver which increases its Zn content. Plasma Fe decreases and Cu increases. 76. Name three enhancers and three inhibitors in the absorption of zinc Enhancers-citric acid/acidic environment; glutathione, tripeptides and amino acids, low zinc status Inhibitors- phytic acid, oxalic acid, polyphenols/tannins, alkalinity from antacids and old age, divalent cations such as calcium and iron 77. Which of these is not a function of zinc? d. Mobilizes vitamin D from adipose 78. Zinc is found in all of the following foods except: D. egg whites 79. How does zinc function in gene expression? How common are these in nature? Zn forms zinc fingers, structures that resemble a finger as it binds to cysteinyl or histidyl residues in the protein. These are present in some transcription factors that bind to Metal Response Elements in promoter regions of selected genes. These can enhance or repress transcription or interact with mRNA to repress translation; Pick 5 Very common, as they are present in 3% of the human genome. 1 required 80. List five products that contain zinc as the active ingredient. Can these be toxic from use? Diaper cream, first aid cream, scar cream, Noxema skin cream, dandruff shampoo, Zn oxide sunscreen, foot powder and makeup. These are not toxic as Zn is sloughed off by the skin. 81. In what population and location was zinc deficiency first discovered? How did it present? Why at this location? Young men and adolescents who were uncommonly short in Iran. They exhibited impaired growth and sexual maturation. They ate vegetarian diets of unleavened pita bread and chickpeas, which are high in phytates and fiber and had the habit of eating (chewing) clay (geophagia) which further bound the zinc. Pick 6 82. List populations at risk for zinc deficiency in middle and high-income countries today and reasons why. Also list those with higher zinc needs. Population at risk: elderly (decreased stomach acidity), vegans (50% greater requirement due to high oxalates), and preschoolers (who are picky eaters). Population with higher need: those with alcoholism, chronic illness, trauma, malabsorption, short bowel syndrome 83. Briefly describe the two basic types of zinc absorption in the body, according to amount in the diet. Include specific names of transporters. Zinc absorption by active transport occurs under normal dietary intakes. It involves the use of Zinc transporters called ZIP. A small amount also is absorbed by Divalent Mineral Transporter 1. When intakes are high (>20 mg) passive paracellular diffusion will occur. 84. Is it recommended to take iron supplements if an individual does not have iron-deficiency anemia? Explain why or why not. Iron supplements should not just be taken with anemia, as anemia can be due to multiple causes, such as deficiencies of folate, Vitamin B12, Vitamin B6 and copper. Excess iron can exceed the carrying capacity of transferrin, the transport protein. Iron promotes bacterial growth and proliferation, leading to infections. Free iron acts as a pro-oxidant by increasing free radicals from the Fenton reaction, an interaction of Fe2+ plus H2O2. Excess iron can also interfere with the absorption of other minerals and cause constipation. 85. Give and explain the three stages of iron deficiency anemia and the diagnostic criteria used. Which occurs first, and which is the least sensitive? Depletion of iron stores (low ferritin); iron deficiency erythropoiesis (low transferrin saturation); iron deficiency anemia (low hemoglobin, hematocrit, and mean corpuscular volume). Depleted iron stores occur first, then the last to occur - anemia, is the least sensitive indicator. 86. Why are eggs not a good source of iron contrary to popular belief? Although eggs are relatively high in iron, eggs contain phosvitin which is the most phosphorylated protein in nature, which inhibits iron absorption. 87. Why would an infant develop an Fe deficiency? What are the symptoms for an infant? Infants can develop an iron deficiency as milk is low in iron, they grow rapidly and have limited stores. Symptoms include pallor, behavioral disturbances, decreased learning ability, impaired cognitive ability, and short attention spans. Pick 3 symptoms 88. List and explain how four nutrients interact with magnesium. Vitamin D: Mg is required for hydroxylation to make the active form of vitamin D. Calcium: Ca competes with Mg for the same transporter system Potassium: K influences the balance of the extracellular/intracellular levels Phosphorus: P inhibits absorption because it causes a precipitate of Mg3(PO4)2 89. What is the tolerable upper level for magnesium? How does this compare to the DRI for adults? The upper level is 350 mg, which is higher than the DRI for females (310 mg) and lower than the DRI for males (400 mg). This is because the upper level has been set only for pharmacological doses, since one cannot develop toxicity from the diet. 90. A very pregnant woman arrives at the emergency room, and you suspect she may have hypermagnesemia. What are her symptoms, and what could be a possible reason? Her symptoms may be diarrhea, nausea, cramps, dehydration, slurred speech, coma, heart failure, and/or kidney failure (pick 4). It could be due to excessive Mg supplements that were given to prevent preeclampsia. 91. Give one reason why zinc is an inhibitor of copper. High levels of zinc stimulate the synthesis of metallothionein. Metallothionein is a metal binding protein that binds metal cations for storage. This protein preferentially binds copper in the enterocyte, thus limiting its absorption and promoting that of zinc. 92. What is unique about the absorption of copper as opposed to other minerals? What is the purpose of this? When absorbed, copper is picked up by chaperone proteins, such as glutathione, Cox 17, Cox 11 or Atox 1 (pick 3). These chaperone proteins help move the copper around the cell for functional uses, store the copper in metallothionein or to the ATP7A protein for export to the blood. 93. What are the two genetic diseases of copper? How do these differ in expression and overall mechanism? What is the most classic symptom of each? Menke's disease is a Cu deficiency due to a mutation in the ATP7A gene in which intestinal Cu cannot be released into the blood. Symptoms are kinky hair (must have) and mental disability. Wilson's disease is a Cu toxicity due to a mutation in the ATP7B gene in which Cu deposits in excess in the liver due to a failure to excrete into the bile. Symptoms are Kayser-Fleischer ring in eye (must have), vomiting, fluid buildup in abdomen and tremors (pick 1) 94. Name four similarities between copper and iron. Both are found in foods in the oxidized form and must be reduced to enter the enterocyte for absorption. Both free copper and iron can damage cells. Both require an acidic environment for absorption and can be inhibited by phytic acid, coffee and an alkaline environment (old age, antacids). 95. Which of the following is not a source of iodine? e. Saltwater taffy 96. Why are goiters more common in regions of the world like Central Africa? Explain, giving both the environmental and biochemical reasons The soil in these areas tends to be low in selenium and the plants, high in goitrogens. Goitrogens are compounds that interfere with iodide uptake and cause goiter. These are found in foods like ground nuts, soybeans, broccoli, cabbage, kale, turnips, and cassava. (pick 4 as 1 pt). Biochemically, the 5' deiodinase enzyme that deiodinates T4 to the active form of T3 requires selenium as a cofactor. 97. What is the most common way that one could develop Cu toxicity? What are the symptoms? What is the upper limit? Drinking acidic juices that have been stored in copper containers. The symptoms are nausea, vomiting, weakness, metallic taste, tachycardia, liver & kidney damage, convulsions (pick 3). The upper limit is 10 mg/d. 98. Discuss the relationships between magnesium and calcium in terms of absorption and metabolism. Magnesium is subject to the same factors as calcium for absorption, with the exception of increased excretion of Mg with intake of alcohol and liquid protein. Magnesium is needed to deposit calcium in the bone and hold it in tooth enamel. Additionally, it functions in transporting Ca2+ across membranes for bodily function. With a magnesium deficiency, calcium calcifies in soft tissues instead of bone and may cause cardiovascular damage. Magnesium also competes with calcium for resorption in the kidneys and binding in smooth muscle. Pick 5 99. What are the symptoms of an iodine deficiency at different ages. Why are these rare in the United States (U.S.)? Where might it be prevalent today? In newborns/infants: a) neurological with mental deficiency, muscle spasticity and b) hypothyroid cretinism with thyroid failure, short stature and learning disability. In children/adolescents: goiter, poor school performance, lower IQ, higher learning disabilities. In adults: goiter or hypothyroidism - decreased body temperature, cold intolerance, weight gain, fatigue, sluggishness, husky voice, low BMR. Deficiencies are rare in the U.S. because salt was iodized in the 1920s. Potassium iodate is commonly used as a dough conditioner for bakery goods. Deficient intakes are found in Russia, Vietnam, Madagascar, Italy, and parts of Africa (pick 1 of these locations). 100. Match the species with its corresponding manganese-related condition. rat deficiency = ataxia human deficiency = milaria crystallina chicken deficiency = perosis plant deficiency = yellowing human toxicity = parkinson's disease 101. How does one develop toxicity from manganese? How might this present? There is no evidence of toxicity from the diet, but toxicity has occurred from inhalation of dust with manganese in mines and welding fields. Symptoms include hyperirritability, violence, hallucinations, libido problems, incoordination, hearing loss, and/or Parkinson's Disease-like symptoms (pick 4). 102. Name three enzymes that require manganese and describe their functions. Arginase: formation of urea Pyruvate carboxylase: creation of oxaloacetate from pyruvate Superoxide Dismutase: catalyzes the dismutation of superoxide radical into oxygen 103. How has dietary manganese intake changed over time in the United States? Manganese consumption has significantly decreased because refined foods have become more prevalent and white flour has replaced whole wheat flour in many products. A diet with 40-50% of energy from whole wheat flour contributes 8.7 mg/day of manganese, whereas white flour as the primary staple contributes only 2.5 mg/day. 104. Name and explain two ways chromium is unlike the trace minerals that have been studied to date. Its essentiality is debated; the US believes it is essential for insulin, sugar, and lipid metabolism, but the European Food Safety Authority does not believe there is sufficient evidence to recognize it as essential. Also, chromium storage in tissues declines with age, unlike other minerals. 105. Explain the role of chromium in insulin signaling. Cr3+ binds to transferrin which then binds to the receptor on the cell. Cr is then released into the cell where four Cr ions bind together with chromodulin to increase kinase activity of the beta subunit of the insulin receptor. 106. List four foods that are high in chromium. What are the US dietary recommendations? Is the amount in the US diet adequate? Explain. Red wine, broccoli, grape juice, potatoes, whole-wheat bread. (Pick 4) The recommendations for men is 35 ug and 25 ug in woman. The US diet is adequate, as it contains 29-54 ug/d. 107. Why is fluoride not a treatment for those with osteoporosis? a toxicity can cause brittle bones and joint stiffness 108. What is the significance of selenoprotein P? This protein carries around most of the selenium in the blood, so it can be used for assessment of selenium status 109. Which of these is best source of selenium? e. brazil nuts 110. Explain the metabolic process and consequences of molybdenum toxicity in humans. Molybdenum is a cofactor in the enzyme xanthine oxidase which creates uric acid that is excreted in the urine. Excess molybdenum can lead to a buildup of uric acid around the joints, leading to inflammation and gout. 111. What are the symptoms of fluorosis, and how this relevant to Texas? Fluorosis occurs when the fluoride in water > 8 ppm. White lines, flecks & brown stains appear on the teeth as they are developing; It occurs in Tyler, Texas. 112. How does selenium deficiency affect animals versus humans? Selenium deficiency can cause muscular dystrophy in animals and muscular pain in humans. 113. Name two enzymes utilized by molybdenum and their functions. Xanthine Oxidase: final enzyme in purine metabolism Aldehyde Oxidase: oxidizes aldehyde into carboxylic acid to metabolize drugs and toxins Pick 2 114. How does molybdenum interact with copper? Molybdenum prevents copper from binding to plasma proteins, and high levels of molybdenum can produce a copper deficiency anemia in cattle, and inhibit angiogenesis (blood vessel growth). 115. Explain how B vitamins participate in the generation of homocysteine/regeneration of methionine. Give several reasons why this is necessary and, also beneficial. Folate = needed for remethylation of homocysteine when SAM is low VIT B12 = picks up methyl from 5-methyl THF to generate THF and methyl B12 which serves as methyl donor methione choline = metabolize to betaine to convert to methionine Homocysteine causes free radicals, lipid peroxidation, inflammation and methionine is a essential amino acid 116. How important is Pantothenic Acid in metabolism? What are its three major functions? Explain the significance of each function with examples. Pantothenic acid is a component of Coenzyme A. The first function of Coenzyme A is to carry acetyl Co A and acyl CoA groups. ~4% of all cellular enzymes use Coenzyme A in metabolism. Coenzyme A also contains 4'-phosphopantheine. This compound is a requirement for the activity of Acyl Carrier Protein, a component of the Fatty Acid Synthase Complex (for fatty acid synthesis). A second major function is the synthesis of other lipids (ketone bodies, cholesterol, bile, steroid hormones). A third function is the de-/acetylation of proteins that prolongs their half-life (delays degradation and stabilizes/destabilizes. 117. Explain what happens to biotin in the biotin cycle and its significance in metabolism. Free or protein bound biotin enters from diet and attaches to holocarboxylase to synthesize and activate enzymes for protein, fat, and carbohydrate metabolism. The free biotin is hydrolyzed by biotinidase. 110. Discuss three ways by which Vitamin C has affected the history of the world. Vitamin c has affected the history of the world by Dr. James Lind discovering that citrus fruit cured scurvy, when Captain James Cook gave nearly 8000 pounds of sauerkraut to take on a two year journey and no one died, and in stopping wars such as the 1815 Waterloo. 119. Briefly explain how vitamin D supplements might affect muscle physiology. Vitamin D supplements might affect muscle physiology by increasing muscle fiber area and diameter and enhancing muscle protein synthesis. 120. Explain the relationships between vitamin K and its deficiency symptoms. Be specific with the biochemistry and physiological effects. Provide specific examples Vitamin K deficiency affects blood coagulation and bone health. Gla-proteins are created during the Vitamin K cycle due to gamma-carboxylation of proteins with glutamic acid residues. A CO2 group is added and then able to bind Ca++ which goes to the Golgi and utilized for blood clotting and binding to proteins in the bone. When decarboxylated, osteocalcin becomes active and acts as a hormone for signaling in the brain, pancreas, muscle, and testis. When carboxylated it is inactive and concentrates in the bone. 121. What are the three mechanisms for increasing blood calcium when dietary intake is low? Blood calcium is raised by: release from bone, reabsorption from the kidneys, and absorption from the small intestine. First, low blood calcium stimulates the release of PTH into the blood by the parathyroid hormone. PTH binds to bone cell receptors to trigger the release of bone calcium into the blood. Second, PTH released from the parathyroid gland travels to the kidneys to hydroxylate calcidiol to form active calcitriol, which promotes the reabsorption of calcium from the kidneys and raises blood calcium. Finally, in the kidneys, calcitriol enters the enterocyte from the kidneys and promotes the synthesis of calbindin; this protein binds calcium and facilitates the active absorption of calcium across the enterocyte and into the blood via a Ca2+ - ATPase pump. 122. What is hypophosphatemia? What are the symptoms? Is it common or rare in the US diet - explain in detail. Name specific examples of populations at risk. Hypophosphatemia is a deficiency of phosphorous. Symptoms are: fatigue, anorexia, muscle weakness, skeletal effects (bone pain, rickets, osteomalacia), calcification of non-skeletal tissues (kidney) (Pick 3) Deficiency is rare, because phosphoric acid is a common additive in foods for preservation. This increases dietary phosphorous intake by 300-1000 mg/day. Common foods with phosphoric acid additives include beverages, processed meat, frozen meals, instant products, and processed cheese. (Pick 3) Populations at risk are primarily individuals who consume large quantities of antacids. Antacids contain aluminum, which can bind to phosphates. Deficiency can also occur with kidney disease, diabetic ketoacidosis, and preterm infants 123. Explain the differences between the ferric and ferrous forms of iron, where and how each is created and why each is important. Include the role of hephaestrin in this process. Inorganic forms: Food iron: Iron is in the ferric Fe3+ (oxidized) form, Vitamin C reduces it to Fe2+ (reduced) form as it is much better absorbed. Absorption: Ferroportin is the protein that exports the Fe2+ out of the cell into the circulation Transport: Transferrin is primary transport throughout circulation. Must be oxidized to Fe3+ to bind. Hephaestin is a supporting protein that reduces Cu2+ to Cu1+ as Fe2+ is oxidized at the basolateral membrane. Storage: Ferritin: Iron must be reduced again to ferrous Fe2+ so it can bind and form a soluble storage form. Hemosiderin, the breakdown product of ferritin is insoluble, is produced by the liver, spleen, bone marrow. Organic (Heme) forms. Fe combines with protoporphyrin IX to form hemoglobin and myoglobin. Hemoglobin carries oxygen in the red blood cells from the lungs to tissues. Myoglobin provides oxygen for muscle metabolism and connective tissue. 124. Explain how vitamin D influences gene expression. Vitamin D influences gene expression by diffusing into the nucleus and binding to Vitamin D receptors (VDR). VDRs also play a role in immunity to prevent autoimmune disorders by down regulating inflammatory cytokines. These heterodimerize with RXR to bind to Vitamin D response elements (VDRE) found in promoter regions of target genes (similar to retinoic acid). It also stabilizes mRNA and enhances protein translation.