Understanding Aerobic Oxidation of Pyruvate
Aerobic oxidation of pyruvate is a crucial metabolic process that occurs in cellular respiration, where pyruvate is converted into acetyl-CoA and subsequently enters the Krebs cycle.
Pyruvate Structure
- Pyruvate (C3H4O3) is a three-carbon compound.
- It contains three carbon atoms, four hydrogen atoms, and three oxygen atoms.
Conversion to Acetyl-CoA
- In the presence of oxygen, pyruvate is decarboxylated to produce acetyl-CoA.
- This process releases one molecule of carbon dioxide (CO2) and requires one molecule of NAD+ (which is reduced to NADH).
Krebs Cycle and Oxygen Requirement
- Acetyl-CoA enters the Krebs cycle, where it undergoes a series of reactions.
- Each complete turn of the Krebs cycle involves the use of oxygen to completely oxidize the carbon atoms.
Calculating Oxygen Usage
- Each acetyl-CoA generates:
- 2 CO2 (which accounts for the 2 carbons from acetyl-CoA).
- 3 NADH.
- 1 FADH2.
- 1 GTP (or ATP).
- The reduced NADH and FADH2 produced will enter the electron transport chain, where oxygen acts as the final electron acceptor.
Final Oxygen Requirement
- For every NADH, 2.5 ATP are generated, and for every FADH2, 1.5 ATP are generated.
- The complete oxidation of one pyruvate requires 5 molecules of O2 in total:
- 2 for the Krebs cycle and 3 for the electron transport chain.
Conclusion
Thus, the number of oxygen atoms required for the aerobic oxidation of one pyruvate is 5. Hence, the correct option is A) 5.

D)12 atoms of oxygen required .