The process that creates the most ATP per glucose molecule metabolized is oxidative phosphorylation.
During cellular respiration, glucose is broken down in a multi-step process to extract energy. This process includes glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation, which is where the majority of ATP is produced.
Glycolysis, which occurs in the cytoplasm, generates a small amount of ATP (2 ATP molecules) along with NADH, which carries electrons to the electron transport chain. The citric acid cycle occurs in the mitochondria and produces additional NADH and FADH2, yielding 2 more ATP molecules.
The total ATP produced from glycolysis and the citric acid cycle is 4 ATP. However, where the magic happens is during oxidative phosphorylation. Here, NADH and FADH2 are used in the electron transport chain, creating a proton gradient across the inner mitochondrial membrane. This gradient drives ATP synthase to produce ATP, resulting in approximately 28 to 32 ATP molecules from the oxidation of each glucose molecule.
Therefore, when you sum it all up, oxidative phosphorylation contributes the largest share of ATP production, allowing for around 30 to 36 ATP molecules per glucose molecule when considering all stages of cellular respiration.