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Thread: help me - electron transport chain

  1. #1 help me - electron transport chain 
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    What would happen to the electron transport chain if the passage of electrons was uncoupled from the transport of H+ into the intermembrane space? Would O2 still be required?


    could you please help me answer this question please
    thank you


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  3. #2  
    Forum Bachelors Degree
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    Dear Salwa,

    I would guess that:

    Complexes I, III and IV would no longer accept and then donate electrons whilst pumping protons from the mitochondrial matrix into the inter-membrane space.

    There would be no proton-motive force; no gradient of protons across the membrane.

    During chemiosmosis, the protons would no longer flow back down their gradient via ATP synthase.

    ATP synthase would no longer harness the proton-motive force to phosphorylate ADP.

    Therefore, the cell would no longer be able to generate ATP in this way.

    In terms of whether or not O2 would still be required, I am not sure. If the electron transport chain was still functioning, though uncoupled, then maybe the cell would still require O2, to "pass" the electrons to at the end of the chain, resulting in the formation of H2O.

    However, the advice of somebody more informed on metabolism would be greatly appreciated.

    All the best,

    Tridimity :wink:


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  4. #3  
    Forum Professor Zwirko's Avatar
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    There's a whole bunch of chemicals called uncoupling agents that can dissipate the proton gradient. Uncoupling can also be carried out as part of normal biological processes, such as in the brown fatty tissue of hibernating animals, where it is used to generate heat.

    The electron transport chain is still functioning when the proton gradient collapses. The major difference in such a situation is that protons are now flowing back across the membrane so quickly that little or no ATP is generated (that is, e- transport is uncoupled from ATP synthesis) and the energy released by the transport of electrons is dissipated as heat. So, you'd still need oxygen for the very reason that tridimity mentioned.
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  5. #4  
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    Hi all............

    If it is uncoupled, then the energy used to drive H+ across the membrane would then be released as heat. Incidentally, skunk cabbage does this in order to heat up and melt the snow around it.



    Thanks
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