What will NOT occur when 2,4-dinitrophenol (an uncoupler of oxidative phosphorylation) is added to actively respiring mitochondria?
A) The P:O ratio will increase.
B) The rate of NADH reoxidation at Complex I will increase.
C) The rate of oxidation of intermediates in the citric acid cycle will increase.
D) Proton export from the matrix will occur.
E) Heat will be released.

Question

Quizplus · Accepted Answer

2,4-Dinitrophenol (DNP) disrupts the proton gradient across the mitochondrial membrane, which decreases the efficiency of ATP synthesis (lowering the P:O ratio), not increasing it. The other options (B, C, D, E) are effects of DNP's action as an uncoupler, which increases the rate of electron transport and associated processes but decreases the efficiency of ATP production.

What Will NOT Occur When 2,4-Dinitrophenol (An Uncoupler of Oxidative