Question

The rate of oxidative phosphorylation Lis regulated by the availability of ADP and P: II. is reduced when the ratio of [NADHV(NAD) is high. III. increases with a higher concentration of reduced cytochromec IV. is regulated by activity of the ADP-ATP translocator. II, IV 1, III, IV 11, 111 o I, III, IV II, IV

Answer 1

Correct Options

I) Is regulated by the availability of ADP and Pi.

Reason: Oxidative phosphorylation requires a supply of NADH, O2, ADP, and Pi.

III) Increases with a higher concentration of reduced cytochrome c.

Reason: Cytochrome c oxidase is the final protein complex in the electron transport chain. So, more reduced cytochrome c means higher will be the oxidation of cytochrome c.

4Cyt cred + O2 + 8H+   --------------> 4Cyt cox + 2H2O + 4H+

The reaction catalyzed is the oxidation of cytochrome c and the reduction of oxygen

IV) Is regulated by activity of the ADP-ATP translocator.

Reason: Inhibitors like atractyloside or bongkrekic acid specifically inhibits ADP-ATP translocase which in turn stops the oxidative phosphorylation. This is the reason why the ADP-ATP translocator is essential.

Incorrect Option

II) Is reduced when the ratio of [NADH]/[NAD+] is high.

- Oxidative phosphorylation increases when [NADH]/[NAD+] is high.

Ans. I,III,IV