A mitochondrial uncoupler such as 2,4-dinitrophenol (DNP) transports H⁺ across the inner membrane independently of ATP synthase. Which combination is expected after DNP exposure?
- A
No change in either O₂ consumption or ATP yield
- B
Increased ATP yield with unchanged O₂ consumption
- C
Decreased O₂ consumption and increased ATP yield
- Dcheck_circle
Increased O₂ consumption and decreased ATP yield per O₂
Explanation
Dissipating the proton gradient lets the electron transport chain run faster (more O₂ used) but ATP synthase has no gradient to drive synthesis (less ATP per O₂). Energy is lost as heat — basis of nonshivering thermogenesis in brown fat.