NADH generated during glycolysis must be converted back to NAD+ if glycolysis is to continue. As discussed in the text, the conversion of NADH to NAD+ can occur by pyruvate accepting the hydrogens (forming lactate) or “shuttling” the hydrogens from NADH across the mitochondrial membrane. The “shuttling” of hydrogens across the mitochondrial membrane requires a specific transport system. Figure 4.9 (see Chap.4) illustrates this process.