<Dd> C H O + 2 NAD + 2 ADP + 2 P → 2 CH COCO + 2 NADH + 2 ATP + 2 H O + 2H </Dd> <P> Pyruvate is CH COCO . P is inorganic phosphate . Two ADP molecules and two P are converted to two ATP and two water molecules via substrate - level phosphorylation . Two molecules of NAD are also reduced to NADH . </P> <P> In oxidative phosphorylation, the energy for ATP formation is derived from an electrochemical proton gradient generated across the inner mitochondrial membrane (or, in the case of bacteria, the plasma membrane) via an electron transport chain . Glycolysis has substrate - level phosphorylation (ATP generated directly at the point of reaction). </P> <P> Fermentation simply means the production of alcohol: grains and fruits are fermented to produce beer and wine . If a food soured, one might say it was' off' or fermented . Here are some definitions of fermentation . They range to informal, general usage to more scientific definitions . </P>

When does fermentation occur in the human body