Now, actually glycolysis produces a total of four ATP molecules. But because it uses up two ATP molecules, the net result is four minus two or two ATP molecules per single glucose molecule. Now, glycolysis takes place in the fluid portion of the cytoplasm of our cell and this is known as the cytosol of our cell. And the production of ATP molecules without using the proteins of the electron transport chain is known as substrate level phosphorylation. Now, the production of ATP molecules using the electron transport chain, as we'll see in just a moment, is known as oxidative phosphorylation. So substrate level phosphorylation is the production of ATP in glycolysis.