In prokaryotes, complete aerobic oxidation of one glucose molecule yields approximately 38 ATP: 2 from glycolysis, 2 from the Krebs cycle, and 34 from oxidative phosphorylation via the electron transport chain. (Eukaryotes yield ~36–38 ATP due to mitochondrial membrane transport costs.) Note: modern estimates suggest 30–32 ATP, but 38 is the traditional exam answer for prokaryotes.