Glycolysis (glyco-sugar; lysis- splitting)

Occurs in the cytosol in ten reactions catalyzed by 10 different enzymes. The result is that: 1. each glucose molecule (C6) is split into two pyruvate molecules (C3); 2. during this process two ATP's are consumed and four are produced for a net gain of 2 ATP's; 3. two molecules of NAD+ are reduced to form two molecules of NADH.      The net results: Glucose + 2NAD+ + 2ADP + 2Pi ® 2pyruvate + 2NADH + 2H+ + 2ATP (water is also involved but not shown)      Glycolysis does not yield much energy but its product, pyruvate, enters the next stage of glucose oxidation, the Krebs cycle. Whether or not pyruvate enters the Krebs cycle depends upon the presence of O2. When O2 is not present pyruvate is converted into lactic acid.