Final answer:
The net product of carbohydrate catabolism in oxidative phosphorylation is typically 36 or 39 molecules of ATP. This variance depends on which shuttle system is used to transport NADH into the mitochondria, affecting the total ATP yield.
Step-by-step explanation:
The net product of carbohydrate metabolism through oxidative phosphorylation is the generation of ATP. During this process, a total of 36 or 39 ATP molecules are produced when glucose derived from glycogen completes oxidation. This number can vary based on the shuttle system used; for example, the glycerol phosphate shuttle yields a lower ATP count than the malate-aspartate shuttle.
In glycogen metabolism, glycolysis produces a net of two ATP, but these are used for the transport of NADH into the mitochondria, so the net ATP gain from glycolysis is effectively zero. However, following glycolysis and the citric acid cycle, NADH and FADH2 are generated, which, in the presence of oxygen within the mitochondria's electron transport chain, facilitate the production of a significant amount of ATP. The glyceraldehyde-3-phosphate dehydrogenase step in glycolysis is critical as it contributes NADH which eventually results in the production of additional ATP during oxidative phosphorylation.