NTR 343 Final Exam Quiz Bank 2022 1. All of the following B vitamins are involved in oxidative decarboxylation of

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