Final answer:
The greatest amount of ATP during cellular respiration is produced by oxidative phosphorylation in the mitochondria, yielding approximately 34 ATP molecules per glucose molecule, compared to just two ATP from fermentation.
Step-by-step explanation:
The part of cellular respiration that produces the greatest amount of ATP is oxidative phosphorylation, which occurs in the mitochondria when both glucose and oxygen are available.
Oxidative phosphorylation, part of the electron transport chain, harnesses the energy released by electrons as they pass through a series of proteins in the inner mitochondrial membrane. The movement of electrons generates a proton gradient, which is then used by ATP synthase to synthesize ATP.
This process is responsible for producing approximately 34 ATP molecules per glucose molecule, when counting the ATP yield from both oxidative phosphorylation and the smaller amount generated through substrate-level phosphorylation in glycolysis and the Krebs cycle. In contrast, fermentation, which occurs in the absence of oxygen, produces only about two ATP molecules per glucose molecule.