The drug 2,4-dinitrophenol (DNP) makes the mitochondrial inner membrane permeable to H. The resulting disruption of the proton gradient inhibits the mitochondrial production of ATP. What additional effect would DNP have on the transport of ATP out of the mitochondrial matrix?

a. None, because ATP export is not coupled to the movement of protons across the inner membrane.

b. ATP transport will increase because ATP synthase will be forced to operate in the "reverse" direction.

c. ATP transport will decrease because less ATP will be available to diffuse across the inner membrane.

d. ATP export will decrease because its carrier exploits the difference in voltage across the inner membrane.

e. None, because the inner membrane is permeable to ATP

Answer:The correct answer is "C": ATP transport will decrease because less ATP is available to diffuse across the membrane.

Explanation:

2,4-dinitrophenol, or DNP, causes uncoupling of oxidative phosphorylation in mitochondria.

Oxidative phosphorylation is a mechanism of ATP sythesis by phosphorylation of ADP for which energy is obtained by eletron transport and it takes place in mitochondria.

DNP is proton ionophore that dissipate proton gradient across inner mitochondrial membrane. In other words, DNP act as an "uncoupler" that makes the inner mitochondrial membrane 'leaky' to protons. Protons move back into the mitochondrial matrix, hence no proton is available to be used by ATP synthase (which produces ATP from ADP and inorganic phosphate using proton gradient.) This results in decrease ATP production. And since ATP is not formed, the energy that is produced from electron transfer is lost as heat.