Uncoupling Oxidative Phosphorylation

Question 1

How is the only way that protons can re-enter the mitochondrial matrix?

Answer 1

Via the Fo portion of ATP synthase

Question 2

What couples electron transport and oxidative phosphorylation?

Answer 2

Proton gradient (which is dependent on the impermeability of the inner mitochondral membrane).

Question 3

What happens to the proton gradient when oxidative phosphorylation is functioning at a minimum (in a resting state)?

Answer 3

H+ pumping eventually stops, inhibiting electron transport.

Question 4

Why do “uncouplers” prevent oxidative phosphorylation/

Answer 4

They increase membrane permeability to H+, thereby dissipating the electrochemical gradient necessary for oxidative phosphorylation.

Question 5

How does DNP (2,4-dinitrophynol) affect electron transport and oxidative phosphorylation?

Answer 5

It allows electron transport to go on unchecked, even when oxidative phosphorylation is functioning at a minimum, thereby destroying the electrochemical gradient.

Question 6

Which compound was used formerly used as a diet pill due to its ability to uncouple e transport and oxidative phosphorylation? What did it cause?

Answer 6

DNP; it caused the electrochemical gradient to be dissipated as heat (deadly).