This illustration shows the eight steps of the citric acid cycle. In the first step, the acetyl group from acetyl CoA is transferred to a four-carbon oxaloacetate molecule to form a six-carbon citrate molecule. In the second step, citrate is rearranged to form isocitrate. In the third step, isocitrate is oxidized to α-ketoglutarate. In the process, one NADH is formed from NAD^{+} and one carbon dioxide is released. In the fourth step, α-ketoglutarate is oxidized and CoA is added, forming succinyl CoA. In the process, another NADH is formed and another carbon dioxide is released. In the fifth step, CoA is released from succinyl CoA, forming succinate. In the process, one GTP is formed, which is later converted into ATP. In the sixth step, succinate is oxidized to fumarate, and one FAD is reduced to FADH_{2}. In the seventh step, fumarate is converted into malate. In the eighth step, malate is oxidized to oxaloacetate, and another NADH is formed.
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