Glycolysis is the major pathway of glucose metabolism and occurs in the cytosol of all cells. It can occur aerobically or anaerobically depending on whether oxygen is available. This is clinically significant because oxidation of glucose under aerobic conditions results in 32 mol of ATP per mol of glucose. However, under anaerobic conditions, only 2 mol of ATP can be produced. Aerobic glycolysis occurs in 2 steps. The first occurs in the cytosol and involves the conversion of glucose to pyruvate with resultant production of NADH. This process alone generates 2 molecules of ATP.