The process that will occur in both the presence and absence of oxygen is glycolysis. Here is a summary of key metabolic processes and their relationship with oxygen:
- Glycolysis: Does not require oxygen and can occur in both aerobic (with oxygen) and anaerobic (without oxygen) conditions.
- Citric Acid Cycle (Krebs cycle): Indirectly requires oxygen because it depends on the electron transport chain that uses oxygen as the final electron acceptor.
- Oxidative Phosphorylation and Electron Transport Chain: Require oxygen directly as oxygen acts as the final electron acceptor.
- Cellular Respiration as a whole varies: aerobic cellular respiration requires oxygen, while anaerobic respiration does not involve oxygen but may involve other molecules as electron acceptors.
- Fermentation: Occurs in the absence of oxygen and is an anaerobic process.
Therefore, among common metabolic processes, glycolysis is the one that can occur whether oxygen is present or absent.