Cellular Respiration (Detailed)

Glycolysis, Krebs cycle, and oxidative phosphorylation step by step

Cellular respiration converts glucose to ATP in three stages. Glycolysis (cytoplasm) splits glucose into 2 pyruvate, yielding 2 ATP and 2 NADH net. The Krebs cycle (mitochondrial matrix) oxidizes acetyl-CoA, producing 2 ATP, 6 NADH, and 2 FADH₂ per glucose. Oxidative phosphorylation (inner mitochondrial membrane) uses the electron transport chain to create a proton gradient, driving ATP synthase to produce ~32-34 ATP. Total yield: ~36-38 ATP per glucose. Without O₂, fermentation produces only 2 ATP per glucose (lactic acid or ethanol pathway).