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  1. #1
    Roxanita is offline Senior Member
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    Biochemical Reactions N*

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    Q.-
    ..................ΔG0′
    V ↔ W........ 4.0
    W ↔ X........+0.4
    X ↔ Y......... 3.4
    Y ↔ Z.........+ 5.7

    From the values of ΔG0′ given in the table, which compound in the overall metabolic pathway V ↔ W ↔ X ↔ Y ↔ Z will accumulate in the largest amount at equilibrium?

    A) V
    B) W
    C) X
    D) Y
    E) Z

  2. #2
    Roxanita is offline Senior Member
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    any clue?

    any clue about this qs? I have my answer which is Z but want to know about your answers and explanations

  3. #3
    Asclepius1's Avatar
    Asclepius1 is offline Ultimate Member 537 points
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    From the question:------------------------------------------------------------------------------------------------------..................ΔG0′
    V ↔ W........ 4.0
    W ↔ X........+0.4
    X ↔ Y......... 3.4
    Y ↔ Z.........+ 5.7
    From the values of ΔG0′ given in the table, which compound in the overall metabolic pathway V ↔ W ↔ X ↔ Y ↔ Z will accumulate in the largest amount at equilibrium? ---------------------------------------------------------------------------------------------------------ΔG0′ = Standard Free Energy Change
    Under STD conditions ΔG0′ can be used to predict the direction a reaction proceeds.
    If ΔG0′ = 0 A < > B at equilibirium (freely reversible)
    If ΔG0′ < 0 A >>> B spontaneous (energy released, often irreversible)
    If ΔG0′ > 0 A <<< B non spontaneous ( energy required)

    Also remember these 2 properties:
    * ΔG0′ of two consecutive reactions are additive and
    * ΔGs of a pathway are additive
    Therefore we have:
    ..................ΔG0′
    V ↔ W........ 4.0
    W ↔ X........+0.4
    X ↔ Y......... 3.4
    Y ↔ Z.........+ 5.7
    ============= Total ΔG0′ = -4.0 +0.4 -3.4 +5.7 = - 1.3 ; which give us the total direction: >>>
    V +W+X+Y >>> W+X+Y+Z
    at the end we would have:
    V >>> Z ΔG0′ = - 1.3 therefore the compound which will accumulate would be: Z
    Ref: Lippincott Biochem pg 64

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    usmlerock is offline Newbie
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    answer is Z

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