Cells derive energy from the oxidation of nutrients such as glucose. The oxidation of glucose to pyruvate occurs through a series of steps called glycolysis. The energy released during these oxidation reactions is used to form adenosine triphosphate, ATP, the energy currency of the cell. The initial steps in glycolysis are the additions of two phosphates to the glucose molecule, at the expense of two molecules of ATP. The result is a six carbon sugar dye phosphate molecule and a one low energy adenosine dye phosphate molecules, or ADP. This six carbon sugar dye phosphate molecule is then split into two three carbon molecules. Most of the three carbon molecules is converted through a series of steps to pyruvate. During these reactions, electrons are transferred to the co-enzyme NAD plus to form NADH and ATP is formed. Under aerobic conditions, the pyruvate is further oxidized to yield more ATP, and under anaerobic conditions, the pyruvate is converted into lactic acid.