In the citric acid cycle, succinate dehydrogenase converts succinate to fumarate with the production also of a molecule of (flavin adenine dinucleotide) that supplies electrons to the electron transport chain. Mitochondrial glycerol-3-phosphate dehydrogenase-2 is an enzyme of the glycerol-3-phosphate shuttle that produces and converts glycerol-3-phosphate into dihydroxyacetone phosphate. The other enzymes are part of the citric acid cycle, but do not produce (aconitase converts citrate to isocitrate, while succinyl-CoA synthetase converts succinyl-CoA to succinate).

The ATP yield from NADH is dependent on how the electrons from the cytoplasmic (glycolytic) NADH are transported into the mitochondria. In muscle, the glycerol-phosphate shuttle occurs, which results in 1.5 ATP per NADH. However, in the heart and liver, the malate-aspartate shuttle occurs, resulting in 2.5 ATP per NADH. This difference explains why some sources list the net ATP from glucose catabolism as 30 ATP, while others list 32 ATP.

Four total molecules of ATP are produced during glycolysis. Note that all of these ATP molecules are created via substrate-level phosphorylation and were made anaerobically. Recall that there are two steps in glycolysis that require ATP as a reactant, and thus, the net ATP production is two ATP per molecule of glucose.

The coenzymes being referred to are and . and are used to generate the bulk of ATP at the electron transport chain. These factors are produced in both glycolysis and the Krebs cycle. In glycolysis the conversion of glyceraldehyde to 1,3-bisphosphoglycerate generates two molecules of per molecule of glucose. The conversion of pyruvate to acetyl-CoA is the next reaction that generates . In the Krebs cycle both and are produced. The reactions that produce are: isocitrate to alpha-ketoglutarate, alpha-ketoglutarate to succinyl-CoA, and malate to oxaloacetate.

The lone reaction that produces is the conversion of succinate to fumarate, which is carried out by an enzyme known as succinate dehydrogenase present in the electron transport chain.