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Movement of H+ in mitochondria

Discussion in 'MCAT Discussions' started by 4s4, Aug 7, 2006.

  1. 4s4

    4s4 Member
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    I'm kind of confused about the whole electron transport chain business and chemiosmotic theory. Is the movement of H+ from the intermembrane space to matrix DOWN the gradient or against? This came up on Kaplan 6 BS and I'm not really getting their explaination. Thanks!
     
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  3. BigRedPremed

    BigRedPremed Senior Member
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    It should be down the gradient.
     
  4. 4s4

    4s4 Member
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    If it's down...then ATP synthesis occurs according to the passage by the "re-entry of protons into the matrix" so when H+ goes down the gradient, then ATP is made...so why does the question (#152) say that "Nigericin is an agent that carries H+ down its concentration gradient" and the answer is that bacteria will be less efficient in making ATP? Shouldn't they be MORE efficient at making ATP?
     
  5. BigRedPremed

    BigRedPremed Senior Member
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    Um, I took the MCAT a year ago and don't know the exact passage you are referencing. My guess is that it would destroy the H+ gradient that is needed to generate ATP. Remember, that ATP is only generated when H+ flows down its gradient THROUGH ATP synthase. If there is a drug that moves H+ down the gradient w/o having to pass through the synthase, you get a reduced gradient w/o generating any ATP. Just my guess.
     
  6. Sol Rosenberg

    Sol Rosenberg Long Live the New Flesh!
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    Good guess. That is the reason.
     
  7. 4s4

    4s4 Member
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    Ohhh, makes sense. Thanks!
     
  8. Foolins

    Foolins Member
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    Because in the mitochondria, the only route for H+ down its gradient should be the channels coupled to ATP synthase.

    If you had some another way of transporting H+ down its gradient without going through the ATP synthase...then it would go back into the matrix for nothing.
     

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