The Krebs cycle and electron transport chain do not require ATP for their operation; rather, the electron transport chain produces ATP. The process is spontaneous due to the favorable oxidation of oxygen to water, with a standard reduction potential (E 1/2) of 0.7V. The Krebs cycle consumes pyruvate, generating NADH, which is essential for establishing the membrane potential that drives ATP synthesis in the electron transport chain.
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fangrz said:I cannot find a website that answers this question, and all diagrams I see do not show that ATP is used. Does this mean that these processes are intrinsically spontaneous? I can see how the electron transport chain is spontaneous, as the oxidation of oxygen to water is favorable (E 1/2=0.7V).
Thank you!Andy Resnick said:The electron transport chain *produces* ATP, it does not consume ATP. It is spontaneous in the sense that H moves along the pH gradient (the membrane potential) to provide the energy, but creating the membrane potential requires consumption of NADH, produced by the Krebs cycle, which consumes sugar (pyruvate) as the energy source.