In the process, we oxidize the malade into oxyloacetate, and now we regenerate this same molecule that we began with, and we can use this same oxalo acetate to basically carry out that same process all over again. So if we sum up all these steps and by the way, this final step, an oxidation reduction reaction, is a very endergonic reaction. It requires about 29.7 kilojoules per mole of energy. Now, if it's so endergonic, why does it actually take place? Well, because it produces the NADH molecule that then goes on into the electron transport chain. And when this is oxidized by the proteins of electron transport chain, that process is exergonic.