Oxygen is essential for cellular respiration, a process that cells use to extract energy from glucose. During cellular respiration, glucose is broken down in a series of steps—glycolysis, pyruvate oxidation, the citric acid (Krebs) cycle, and oxidative phosphorylation—ultimately producing ATP, the energy currency of cells. Oxygen acts as the final electron acceptor in the electron transport chain during oxidative phosphorylation, allowing the production of water and enabling the generation of a large amount of ATP. Without oxygen, this efficient energy production process would not occur, and cells would rely on less efficient anaerobic pathways.
Key Steps in Cellular Respiration
- Glycolysis: Glucose (a 6-carbon sugar) is split into two molecules of pyruvate (3-carbons each), producing ATP and NADH.
- Pyruvate Oxidation: Pyruvate enters mitochondria, where it is converted to acetyl-CoA, releasing carbon dioxide and generating NADH.
- Citric Acid Cycle: Acetyl-CoA combines in a cycle producing ATP, NADH, FADH2, and releasing carbon dioxide.
- Oxidative Phosphorylation: NADH and FADH2 donate electrons to the electron transport chain, where oxygen accepts the electrons to form water. The flow of electrons drives ATP synthesis.
Role of Oxygen
Oxygen is crucial as the terminal electron acceptor in the electron transport chain. It binds electrons and protons to form water, which prevents electron backup and allows continuous ATP production. This process yields about 36-38 ATP molecules per glucose, making aerobic respiration highly efficient.
Thus, oxygen is vital for enabling cells to obtain energy from glucose efficiently through cellular respiration.
