Krebs cycle uses two molecules of pyruvic acid which are formed during glycolysis. This also results in high-energy molecules of NADH and FADH2 as well as ATP. During the process of Krebs cycle, both molecules are broken down by an enzyme, which results in the release of CO2 from one carbon atom. The remaining carbon atoms are then combined with a coenzyme which is called coenzyme A. This reaction then forms acetyl-CoA.
