Step 1: Glycolysis. In glycolysis, glucose—a six-carbon sugar—undergoes a series of chemical transformations. In the end, it gets converted into two molecules of pyruvate, a three-carbon organic molecule. In these reactions, ATP is made, and \text{NAD}^+NAD + N, A, D, superscript is converted to {NADH}NADHN, A, D, H.
Step 2:Pyruvate oxidation. Each pyruvate from glycolysis goes into the mitochondrial matrix—the innermost compartment of mitochondria. There, it’s converted into a two-carbon molecule bound to Co-enzyme A, known as acetyl CoA. Carbon dioxide is released and NADH is generated.
Step 3:Citric acid cycle. The acetyl CoA made in the last step combines with a four carbon molecule and goes through a cycle or reaction, ultimately regenerating the four carbon starting molecule.
