Question

Which is the source of energy used to make ATP by oxidative phosphorylation?

• A. Oxygen
• B. High-energy phosphate bonds
• C. The proton motive force
• D. Inorganic phosphate

Hint:

The proton motive force is critical for ATP production in oxidative phosphorylation, driving the action of ATP synthase.

Answer 1

The Correct Option is C

The proton motive force (PMF) is the primary source of energy used to make ATP during oxidative phosphorylation. It is generated by the electron transport chain, which pumps protons (H⁺) across the mitochondrial membrane, creating an electrochemical gradient. This gradient is then used by ATP synthase to synthesize ATP from ADP and inorganic phosphate.

(1) Proton Motive Force (PMF):
- The PMF is the electrochemical gradient created by the pumping of protons into the intermembrane space of the mitochondria. The energy stored in this gradient is harnessed by ATP synthase to produce ATP.

(2) Why Other Options Are Incorrect:
- Oxygen (Option 1) is the final electron acceptor in the electron transport chain, but it does not directly provide the energy to make ATP.
- High-energy phosphate bonds (Option 2) are present in ATP and other molecules, but the energy required for oxidative phosphorylation comes from the proton gradient.
- Inorganic phosphate (Option 4) is used in the phosphorylation of ADP to ATP, but the energy required for this process is derived from the proton motive force.

Conclusion: The energy used to make ATP during oxidative phosphorylation comes from the proton motive force created by the electron transport chain.