The Krebs cycle is an eight step process. Half of them are dehydrogenase steps, which means that 50% of this whole thing is creating these things we're just talking about now, which is electron carriers. So it goes from a six carbon molecule to a five in the form of carbon dioxide. We take NAD+, steel-too-hydrogen with an extra electron, toss one of those hydrogen in the solution as a hydrogen ion, and now we're left with alpha-keto-glutarate - a five carbon molecule. The next step is very similar to the one we just went through, where we go from a five carbon now to a four carbon. And yeah