Isolated mitochondria were given succinate (electron donor) and ADP. O2 consumption was measured. Then DNP (a proton ionophore) was added at minute 5.
DNP increases O2 consumption because:
- Acheck_circle
It dissipates the proton gradient, allowing the ETC to run without ATP synthesis constraint.
- B
It blocks ATP synthase.
- C
It increases substrate availability.
- D
It donates extra electrons to the chain.
Explanation
DNP is an uncoupler: it carries protons across the inner mitochondrial membrane, collapsing the gradient. The ETC pumps faster (and burns more O2) trying to restore it, but ATP yield plummets and energy is dissipated as heat.