does the krebs cycle require oxygen

Sourav PanApril 18, 2025

Answered

The Krebs cycle itself does not directly consume molecular oxygen (O₂) during its enzymatic reactions. However, it is considered an aerobic process because it relies on the presence of oxygen indirectly. The high-energy electron carriers produced in the cycle (NADH and FADH₂) transfer their electrons to the electron transport chain, where oxygen acts as the final electron acceptor. Without oxygen to maintain the flow of electrons in this chain, the regeneration of NAD⁺ and FAD would cease, halting the Krebs cycle due to a lack of available oxidized cofactors. Thus, while oxygen is not a direct reactant in the Krebs cycle, its presence is essential for the cycle’s continuation.