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Thread: Q-1) Vitamins

  1. #1
    Roxanita is offline Senior Member
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    Q-1) Vitamins

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    Q.- The two vitamins necessary for nucleic acid synthesis are folate and

    A) vitamin A.

    B) vitamin B1 (thiamine).

    C) Vitamin B3 (niacin).

    D) Vitamin B12 (cobalamin).

    E) Vitamin C (ascorbic acid).

  2. #2
    BioPatel is offline Member
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    Is it SAM the Methyl Man? B12
    Methylmalonyl-CoA Mutase
    catalyzes a molecular rearrangement in which the branched carbon chain
    of methylmalonyl-CoA is converted tothe linear carbon chain of
    succinyl-CoA. The carboxyl that is in ester linkageto the thiol of coenzyme A is shifted to an adjacent carbon atom, with opposite shift of ahydrogen atom.
    Recall that coenzyme A is a large molecule, as shown at right.

    Coenzyme B12 (vitamin B12, also called cobalamin) is the prosthetic group of Methylmalonyl-CoA Mutase. In mammals coenzyme B12 is a cofactor for this reaction and is involved also in methyl group transfer. In bacteria, coenzyme B12 is involved in a larger variety of carbon-skeleton rearrangement and elimination reactions.
    Coenzyme B12
    bound to Methylmalonyl-CoA Mutase is displayed at right in ball and
    stick display, with the cobalt atom in spacefill display. See also
    diagrams in the Stadtman website at NIH and in the Voet & Voet textbook pages 922-927. Coenzyme B12 contains a heme-like corrinring with a cobalt ion coordinated to 4ring nitrogen atoms.
    In free vitamin B12, the cobalt atom has two axial ligands: a ring N atom of dimethylbenzimidazole (covalently linked to the corrin ring, shown above extended away from the Co), and the methyl C atom of 5'-deoxyadenosine (not shown here).
    When coenzyme B12
    is bound to the Methylmalonyl CoA Mutase enzyme, the
    dimethylbenzimidazole ligand extends away from the Co is replaced by an
    enzyme histidine N.

    Color key: C O N P Co
    Homolytic cleavage of the deoxyadenosyl C-Co bond yields a deoxyadenosyl carbonradical as Co3+ becomes Co2+.
    Reaction of this with methylmalonyl-CoA generates a radical
    substrateintermediate and 5'-deoxyadenosine. Following rearrangement of
    the substrate, the product radical abstracts a hydrogen atom from the
    methyl group of 5'-deoxyadenosine. This yield succinyl-CoA and the
    5'-deoxyadenosyl radical, which reacts with coenzyme B12 to reestablish the deoxyadenosyl C-Co bond. Explore
    at right Methylmalonyl-CoA Mutase, with desulfo-coenzyme A (CoA analog
    lacking the reactive thiol) present at the active site.

    Methylmalonyl-CoA
    Mutase

    Vitamin B12is synthesized only by bacteria. Ruminant animals obtain the vitamin frombacteria in their digestive system. Humans obtain vitamin B12 from meat or dairyproducts. Vitamin B12 is absorbed by cells in the upper part ofthe human small intestine, via receptor-mediated endocytosis. Vitamin B12 synthesizedby bacteria in the large intestine is unavailable. Strict vegetarians eventuallybecome deficient in vitamin B12.

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    Roxanita is offline Senior Member
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    right

    Right BioPatel,

    D) Vitamin B12 (cobalamin)

    Folate and vitamin B12 are necessary for nucleic acid synthesis.

  4. #4
    rumki8 is offline Newbie 510 points
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    Centrum Multi Vitamin

    Hi friends, I am taking Centrum Multi Vitamin which is chewable. I canít take large pills. I want to know the cause to the upset stomach & gas with in 10 minutes from a vitamin? When taking vitamins should you take it with food? Maybe eat before/after taking the vitamin? Is there anyway to take a multi vitamin without having gas/upset stomach? Please help. Thanks in advance!

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    Dr. Mixmasta is offline Junior Member
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    Yeap

    Yeap Its B12

  6. #6
    starry_night is offline Junior Member 511 points
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    bump...................................

  7. #7
    Norman11 is offline Newbie 510 points
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    Multiple vitamin-mineral supplements, sometimes known as multivitamin-mineral supplements, contain a variable number of essential and/or non-essential nutrients.

  8. #8
    windsorStudentmd is offline Newbie 510 points
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    More information on this... check out the KISSPrep Biochem videos!

  9. #9
    windsorStudentmd is offline Newbie 510 points
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    I would say thiamine... cause B1 is needed for transketolase activity.

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