De citroenzuurcyclus: output

The main aim of the citric acid cycle is to generate energy from the electrons harvested from sugar molecules like glucose.

Upon entering the citric acid cycle, acetyl-CoA goes through a series of reactions losing its acetyl group as carbon dioxide.

During the oxidative steps of the cycle, the electrons are transferred to NAD⁺, generating NADH.

GTP produced from the conversion of succinyl-CoA to succinate is readily converted to ATP.

In the next reaction, the electrons from succinate oxidation are used to reduce FAD to FADH₂.

Thus, each turn of the TCA cycle generates two CO₂ molecules, three NADH, one FADH₂, and one ATP.

The cycle must go around twice since oxidation of each glucose molecule generates two pyruvates.

Therefore, for every glucose molecule oxidized, the citric acid cycle generates four CO₂, six NADH, two FADH₂, and two ATP molecules.

The coenzymes—NADH and FADH₂—generated from the TCA cycle are utilized during oxidative phosphorylation to produce more ATP.