Cellular respiration is a complex biochemical process that converts the chemical energy stored in glucose into ATP (adenosine triphosphate). It occurs in several stages, beginning with glycolysis, where glucose is broken down into pyruvate in the cytoplasm. This is followed by the Krebs cycle in the mitochondria, where further breakdown occurs, releasing CO2 and transferring electrons to energy carriers like NADH and FADH2. Finally, oxidative phosphorylation uses these electrons in the electron transport chain to generate ATP, while oxygen acts as the final electron acceptor, producing water as a byproduct.