BIBC 120 Water Soluble Vitamins

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  1. Where are water-soluble vitamins absorbed?
    small intestine
  2. What do water-soluble vitamins function as?
  3. Which has more potential for toxicity from over consumption: water-soluble or fat-soluble vitamins?
    fat-soluble vitamins
  4. What kind of nutrients are vitamins?
    essential micronutrients
  5. What is the key for vitamin intake?
    variety in diet
  6. What must happen to vitamins before they are absorbed?
    the proteins that they are bound to must be digested away
  7. What can affect the bioavailability of vitamins?
    dietary factors
  8. What is the most important metabolic organ?
  9. What kind of coenzyme is vitamin C?
    electron donor coenzyme
  10. What are choline and carnitine?
    conditionally essential nutrients
  11. How are vitamins removed from foods?
    Vitamins are often removed by processing (ie. milling of grains)
  12. What is the difference between fortified and enriched foods?
    • fortified: any addition of nutrients
    • enriched: more stringent; must contain FDA specified levels of vitamins; only for grain based foods
  13. For whom can vitamin supplements be beneficial?
    pregnant women or when diet omits a large amount of food variety (vegan diet)
  14. Name two water-soluble vitamins
    B12, C
  15. What is Vitamin B12 also known as?
  16. What does vitamin B12 contain?
  17. Where can vitamin B12 only be synthesized?
    Vitamin B12 can only be synthesized by bacterial sources - gut microbiota
  18. What is the only source of vitamin B12?
    animal dietary sources
  19. What are two good sources of vitamin B12?
    liver and clams
  20. What two things does vitamin B12 bind to?
    • Intrinsic Factor (IF)
    • R protein
  21. Where is Intrinsic Factor secreted from?
    parietal cells in gastric pits
  22. IF/B12 complex binds to what?
    receptors on brush-border epithelium for transport
  23. What does the R protein do?
    protects B12 in stomach
  24. What are the only two reactions involving the coenzyme vitamin B12?
    • Methionine metabolism
    • Propionate metabolism
  25. What is folate?
    Another Vitamin B (B9)
  26. What does tetrahydrafolate (THF) do?
    accepts/donates single carbon units in amino acid and nucleotide metabolism
  27. Which step of the creation of methyl-THF is irreversible?
    the final step from N5, N10-methylene-THF to N5-methyl-THF
  28. What is the only metabolic chemical reaction that uses methyl-THF?
    methionine metabolism
  29. What are some consequences of Vitamin B12 deficiency?
    • pernicious anemia - lack of red blood cells
    • no THF available for nucleotide synthesis
    • increase in serum levels of homocysteine increases risk for heart disease
  30. What are the consequences of vitamin B12 deficiency in propionate metabolism?
    odd chain fatty acid accumulation in phospholipids of neuronal membranes cause neurodegenerative symptoms
  31. What do elderly individuals have a hard time producing?
    Intrinsic Factor
  32. Which two deficiencies are hard to distinguish and are often treated by supplements of both vitamins?
    folate and B12
  33. What does Vitamin C do?
    • donor/acceptor of single electrons
    • acts as a coenzyme for specific biosynthetic reactions
    • donates electron to reduce metal ion cofactors that have donated an electron in the reaction
  34. How is vitamin C "recharged" (reduced)?
    dehydroascorbate reductase using glutathione as electron source
  35. Where is vitamin C synthesized?
    from glucose in plants
  36. Which two animals can synthesize vitamin C?
    rats and chicken
  37. What are two good sources of vitamin C?
    sweet red peppers (raw) and orange juice (fresh)
  38. Does vitamin C help to prevent rando oxidative damage in the body from free radicals and peroxides?
    efficient at reducing superoxide radicals and hydrogen peroxide in vitro

    no evidence yet that vitamin C acts to reduce random oxidative damage in vivo
Card Set
BIBC 120 Water Soluble Vitamins
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