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    When reduced NAD+ goes to NADH,H+.
    1. Does that mean it takes two hydrogen atoms to reduce NAD? (both from the substrate?)
    2. Does just the NADH get transported for oxidative phosphorylation or is the NADH bonded to the H+ and they are both transported?

    Also in the diagram of the Krebs cycle in my book it shows and describes, a pair of hydrogen atoms being removed at 4 points. However that is a loss of 8 hydrogen atoms per cycle, when the input (acetate) has only 3 hydrogen atoms.
    Where do the extra hydrogen's come from?
    Is it only one hydrogen atom removed each time the substrate is dehydrogenated?

    Also considering that 10 NADP and 2 FAD are made from one molecule of glucose and glucose has 12 hydrogen atoms, surely only one atom of hydrogen is removed from the substrate when it is dehydrogenated to reduce NAD.
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    1. Does that mean it takes two hydrogen atoms to reduce NAD? (both from the substrate?)

    Reduced NAD holds two hydrogen atoms.

    2. Does just the NADH get transported for oxidative phosphorylation or is the NADH bonded to the H+ and they are both transported?

    Reduced NAD (and reduced FAD) is what is used in oxidative phosphorylation. Their main function is to carry the two hydrogen atoms where they donate them to oxidative phosphorylation (The NAD then becomes re-oxidised for use again in Glycolysis, The link reaction and Krebs cycle).

    Also in the diagram of the Krebs cycle in my book it shows and describes, a pair of hydrogen atoms being removed at 4 points. However that is a loss of 8 hydrogen atoms per cycle, when the input (acetate) has only 3 hydrogen atoms.
    Where do the extra hydrogen's come from?
    Is it only one hydrogen atom removed each time the substrate is dehydrogenated?

    No, remember that acetate combines with oxloacetate to form Citrate. Krebs cycle is the regeneration of oxloacetate. For each turn of the Krebs cycle:
    • 3 reduced NAD (with two hydrogen atoms)
    • 1 reduced FAD (with two hydrogen atoms)
    • Also 1 x CO2 and 1 ATP is formed.
    That makes (3x2)+(1x2) = 8 hydrogen atoms released.

    Remember that there are two turns of Krebs from each glucose molecule.



    Also considering that 10 NADP (NADP IS INVOLVED IN PHOTOSYNTHESIS AHHH) and 2 FAD are made from one molecule of glucose and glucose has 12 hydrogen atoms, surely only one atom of hydrogen is removed from the substrate when it is dehydrogenated to reduce NAD.

    I'm not sure about this one, but personally I don't think we have to worry too much about the specific number of hydrogen atoms each substrate has - I've been through the specification and through two textbooks and not seen reference to how many hydrogen atoms each product has at each stage. Rather that NAD receives two hydrogen atoms to become reduced NAD and that the more hydrogen atoms a substrate has (EG: carbohydrates, Lipids) the more ATP can be generated from it.


    Sorry if some of my terms are different to yours, we don't use NADH and what not.

    Ben x
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    (Original post by Benn_95)
    1. Does that mean it takes two hydrogen atoms to reduce NAD? (both from the substrate?)

    Reduced NAD holds two hydrogen atoms.

    2. Does just the NADH get transported for oxidative phosphorylation or is the NADH bonded to the H+ and they are both transported?

    Reduced NAD (and reduced FAD) is what is used in oxidative phosphorylation. Their main function is to carry the two hydrogen atoms where they donate them to oxidative phosphorylation (The NAD then becomes re-oxidised for use again in Glycolysis, The link reaction and Krebs cycle).

    Also in the diagram of the Krebs cycle in my book it shows and describes, a pair of hydrogen atoms being removed at 4 points. However that is a loss of 8 hydrogen atoms per cycle, when the input (acetate) has only 3 hydrogen atoms.
    Where do the extra hydrogen's come from?
    Is it only one hydrogen atom removed each time the substrate is dehydrogenated?

    No, remember that acetate combines with oxloacetate to form Citrate. Krebs cycle is the regeneration of oxloacetate. For each turn of the Krebs cycle:
    • 3 reduced NAD (with two hydrogen atoms)
    • 1 reduced FAD (with two hydrogen atoms)
    • Also 1 x CO2 and 1 ATP is formed.
    That makes (3x2)+(1x2) = 8 hydrogen atoms released.

    Remember that there are two turns of Krebs from each glucose molecule.



    Also considering that 10 NADP (NADP IS INVOLVED IN PHOTOSYNTHESIS AHHH) and 2 FAD are made from one molecule of glucose and glucose has 12 hydrogen atoms, surely only one atom of hydrogen is removed from the substrate when it is dehydrogenated to reduce NAD.

    I'm not sure about this one, but personally I don't think we have to worry too much about the specific number of hydrogen atoms each substrate has - I've been through the specification and through two textbooks and not seen reference to how many hydrogen atoms each product has at each stage. Rather that NAD receives two hydrogen atoms to become reduced NAD and that the more hydrogen atoms a substrate has (EG: carbohydrates, Lipids) the more ATP can be generated from it.




    Sorry if some of my terms are different to yours, we don't use NADH and what not.

    Ben x
    But oxaloacetate is only a catalyst (it is reacted with the reactant but then regenerated in the same quantity). And acetate, having only 3 H atoms cannot possibly have 8 H atoms removed from it.

    It's fine, I would just prefer to understand whats happening rather than just memorize it.
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    (Original post by Nick_)
    But oxaloacetate is only a catalyst (it is reacted with the reactant but then regenerated in the same quantity). And acetate, having only 3 H atoms cannot possibly have 8 H atoms removed from it.

    It's fine, I would just prefer to understand whats happening rather than just memorize it.
    I'm pretty sure 'acetate' is another name for ethanoic acid, which is CH3COOH

    OP, if you'd like more information about things outside the spec to help you understand it better (biochemical knowledge of the Krebs cycle isn't required at A-level), then ask your teachers.
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    (Original post by Pride)
    I'm pretty sure 'acetate' is another name for ethanoic acid, which is CH3COOH

    OP, if you'd like more information about things outside the spec to help you understand it better (biochemical knowledge of the Krebs cycle isn't required at A-level), then ask your teachers.
    sorry 4, still not 8 althogh 4 would make sence if they only took one hydrogen each. And teachers are absolutely useless at anything it doesn't explicitly say in the textbook
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    (Original post by Nick_)
    sorry 4, still not 8 althogh 4 would make sence if they only took one hydrogen each. And teachers are absolutely useless at anything it doesn't explicitly say in the textbook
    There's a reason for that, it's because it won't be asked, and you won't get marks for stating it. You don't need knowledge of the biochemistry, just the names of the compounds, and how many carbon atoms they have.

    your teachers also may not know the answers to your questions. If all fails, there is wikipedia.
 
 
 
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