The Krebs Citric Acid cycle is a biochemical pathway that releases carbon dioxide and hydrogen ions and results in the formation of ATP. A six-carbon citric acid molecule is formed when the two-carbon acetyl group from acetyl CO-A combines with a four-carbon(oxaloacetic acid) and coenzyme A is regenerated. Two hydrogen and CO2 are given off and the hydrogen is captured by NAD to from NADH2 and a five-carbon is formed. Two more hydrogen ions and another CO2 are given off to from another NADH2. An ATP is then generated with some of the energy of the reaction and a four-carbon is formed. Two more hydrogen and CO2 ions are released to be captured by FAD and FADH2 is produced. The four carbon oxaloacetic acid is regenerated and the cycle starts again.(1)