Answer:
reduce NAD+ and FAD.
Step-by-step explanation:
In the Krebs cycle the carbons donated by the acetyl group are oxidized to CO2 and the electrons pass to the electron transporters. As in glycolysis, a specific enzyme is involved in each step. Coenzyme A is the link between the oxidation of pyruvic acid and the Krebs cycle. In the course of these steps, some of the energy released by the oxidation of the CH and CC bonds is used to convert ADP to ATP (one molecule per cycle), and part is used to produce NADH and H + from NAD (three molecules per cycle). In addition, a fraction of the energy is used to reduce a second electron transporter, the FAD. For each turn of the cycle, a molecule of FADH2 is formed from FAD. O2 is not required for the Krebs cycle: electrons and protons removed in carbon oxidation are accepted by NAD + and FAD. It takes two turns of the cycle to complete the oxidation of a glucose molecule. Thus, the total energy efficiency of the Krebs cycle for one glucose molecule is two molecules of ATP, six molecules of NADH and two molecules of FADH2.