Glycolysis is a partial breakdown of a six-carbon glucose molecule into two, three-carbon molecules of pyruvate, 2NADH +2H+, and 2 net ATP as a result of substrate-level phosphorylation. Glycolysis occurs in the cytoplasm of the cell. The overall reaction is:
glucose (6C) + 2 NAD+ 2 ADP +2 inorganic phosphates (Pi)
yields 2 pyruvate (3C) + 2 NADH + 2 H+ + 2 net ATP