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    Hi,
    Please can someone clarify this? My book says:
    Two hydrogen atoms (with their electrons) are removed from each triose phosphate molecule (the substrate), this involves dehydrogenase enzymes which are aided by coenzyme NAD, which is a hydrogen acceptor. NAD combines with the hydrogen atoms becoming reduced NAD.
    So at this stage of glycolysis, two molecules of NAD are reduced per molecule of glucose. Also at this stage, two molecules of ATP are formed. This is called substrate level phosphorylation.

    How exactly are the two molecules of ATP formed? How does reducing NAD form them?

    Thanks in advance.
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    Basically the two modules of NADH (reduced NAD) enter the mitochondrion and are used by complex one to pump protons from one side of the mitochondrial membrane to the other. This process causes a chemical gradent. This is then used by ATP synthase to pump protons back into the mitochondria. This pumping produces energy that can be used to make ATP.

    Again I may of simplified this but I hope it gets the point across.
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    (Original post by joshed)
    Basically the two modules of NADH (reduced NAD) enter the mitochondrion and are used by complex one to pump protons from one side of the mitochondrial membrane to the other. This process causes a chemical gradent. This is then used by ATP synthase to pump protons back into the mitochondria. This pumping produces energy that can be used to make ATP.

    Again I may of simplified this but I hope it gets the point across.
    Whilst true, the textbook clearly says 'at this stage' and it wouldn't count as 'substrate-level phosphorylation' (it also wouldn't be two molecules of ATP - it would be more like 7).

    During glycolysis, NAD becomes NADH in a reaction creating 1,3 biphosphoglycerate (adding a phosphate). This rapidly becomes 3-phosphoglycerate, losing one of the phosphates to ADP (thereby creating the ATP). As this happens twice for each glucose molecule, it creates 2 ATP.

    Hope that is clear - that text book seems very wordy! To know it in any more detail than that woluld be going into molecule configurations and energy levels - basically the NAD reducing allows the phosphate to be added and then lost creating ATP. The glycolysis page of wikipeidia has the complete glycolysis diagram - you can see this step for yourself.
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    (Original post by joshed)
    Basically the two modules of NADH (reduced NAD) enter the mitochondrion and are used by complex one to pump protons from one side of the mitochondrial membrane to the other. This process causes a chemical gradent. This is then used by ATP synthase to pump protons back into the mitochondria. This pumping produces energy that can be used to make ATP.

    Again I may of simplified this but I hope it gets the point across.
    This is oxidative phosphorylation, the 4th step of aerobic respiration, where the bulk of ATP is produced by the proton motive force through ATP synthase to combine ADP + Pi -> ATP.

    Substrate level phosphorylation is the substrate (glucose derivative e.g. hexose-1,6-bisphosphate) losing a phosphate group which is then combined with ADP to produce ATP.
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    (Original post by nexttime)
    Whilst true, the textbook clearly says 'at this stage' and it wouldn't count as 'substrate-level phosphorylation' (it also wouldn't be two molecules of ATP - it would be more like 7).

    During glycolysis, NAD becomes NADH in a reaction creating 1,3 biphosphoglycerate (adding a phosphate). This rapidly becomes 3-phosphoglycerate, losing one of the phosphates to ADP (thereby creating the ATP). As this happens twice for each glucose molecule, it creates 2 ATP.

    Hope that is clear - that text book seems very wordy! To know it in any more detail than that woluld be going into molecule configurations and energy levels - basically the NAD reducing allows the phosphate to be added and then lost creating ATP. The glycolysis page of wikipeidia has the complete glycolysis diagram - you can see this step for yourself.
    Thanks for this. I had a look at the diagram and my book just said 4 enzyme catalysed reactions, but now that I know some of those reactions involve the breaking down of another molecule with phosphate groups that makes sense.
 
 
 
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