I don't know which source i'm going to follow.

Some say its 3 molecules NADH per cycle → 2 cycles × (3 NADH) = 6 NADH

Some say its 4 molecules NADH per cycle instead?

  • 1
    $\begingroup$ This question is not off topic for the reason you chose. OP is clearly asking: "there are two different information out there, which one is correct?" The main point in this question is: is respiration divided in 3 or 4 phases? That is, dehydrogenation of pyruvate is part of Krebs cycle or not? That being the case, the question is clearly valid and useful, as you can see by the number of upvotes. $\endgroup$
    – user24284
    May 23, 2017 at 23:57

2 Answers 2


This is slightly depending on which reaction you want to include into the cycle. I count four:

  • One when Pyruvate is converted to Acetyl-CoA,

  • one when Isocitrate is converted to α-Ketoglutarate,

  • one for the reaction of α-Ketoglutarate to Succinyl-CoA and

  • finally one for the reaction of Malate to Oxaloacetate.

If you see the reaction of Pyruvate as happening outside of the cycle, it's only the later three. See this image (from here) for an overview:

enter image description here


enter image description here The alpha-ketoglutaric dehydrogenation to form Co~A.The NADH energy is released.Therefore 6 molecules of NADH is produced You can see the above picture to understand better.

  • 2
    $\begingroup$ This question already has a good answer, upvoted by the community. Even so you decided to write an answer which not only is poorly worded and confusing but it is also wrong. $\endgroup$
    – user24284
    May 23, 2017 at 14:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.