You are studying the effects of a compound on the respiratory activity of isolated mitochondria. Your experiments demonstrate that oxygen consumption increases as expected when pyruvate and malate are used as well as when succinate is added. Addition of the test compound results in a significant rate of oxygen consumption. These results most closely resemble the effects that would be seen by the addition of which of the following to your system?
A) antimycin A
B) carbon monoxide
C) cyanide
D) dinitrophenol
E) rotenone

Question

Quizplus · Accepted Answer

Dinitrophenol uncouples oxidative phosphorylation, leading to increased oxygen consumption as the electron transport chain works harder to maintain the proton gradient.  Dinitrophenol, DNP, is a chemical uncoupler of electron transport. Uncouplers cause increased oxygen consumption. DNP functions by allowing protons to flow back into the matrix of the mitochondria through the inner mitochondrial membrane which dissipates the electrochemical gradient and preventing ATP synthesis. Since the proton motive force (PMF) across the membrane is lost, there is no longer a gradient to restrict the rate of electron flow; as a result electron transport accelerates resulting in increased oxygen consumption.

You Are Studying the Effects of a Compound on the Respiratory