A worker in a munitions factory presents with high fever, profuse sweating, and rapid weight loss over several weeks. Investigations show elevated metabolic rate with normal thyroid function tests. His mitochondria are able to consume oxygen at a high rate while ATP production falls markedly. The toxin he was exposed to acts by which mechanism?
- A Blocking the transfer of electrons from cytochrome c to oxygen
- B Inhibiting the adenine nucleotide translocase
- C Carrying protons across the inner mitochondrial membrane, dissipating the proton gradient ✓
- D Binding the beta subunit of the F1 portion of ATP synthase
Correct answer: C. Carrying protons across the inner mitochondrial membrane, dissipating the proton gradient
Explanation
The presentation is classic for an uncoupler such as 2,4-dinitrophenol. Uncouplers are lipid soluble weak acids that shuttle protons back into the matrix across the inner membrane, bypassing ATP synthase. Electron transport and oxygen consumption continue unchecked and the energy escapes as heat, causing hyperthermia. Cyanide blocks electron flow (option A), which would reduce oxygen consumption, not raise it.
Reference: Lehninger Principles of Biochemistry (Nelson and Cox), 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.