original glucose molecule's energy. But where no oxygen is available, each pyruvic acid molecule is subjected to a reduction reaction by a molecule of NADre to produce two molecules of either ethanol or lactic acid and two of NADox. This process is called fermentation, and although it does reoxidize a cell's typically limited supply of NAD so that the glycolysis chain of reactions can
keep going, fermentation leaves much of the glucose molecule's original energy
