Question

In oxidative photophosphorylation, the last 3 steps are as follows
Co-Q $\to$ Cyt-c $\to$ Cyt-$a{a}_3$ $\to$ $O_2$

• A. Co-Q $\to$ Cyt-c is $H^{+}$ absorbing site
• B. Cyt-$a{a}_3$ $\to$ $O_2,H^{+}$ yielding site
• C. CoQ $\to$ Cyt-c is $H^{+}$ yielding site and Cyt-$a{a}_3$ $\to$ $O_2$ is $H^{+}$ absorbing site
• D. no $H^{+}$ is absorbed or released

Answer 1

The correct option is C CoQ $\to$ Cyt-c is $H^{+}$ yielding site and Cyt-$a{a}_3$ $\to$ $O_2$ is $H^{+}$ absorbing site

In electron transport chain, electrons are transported through a series of carriers. NADH dehydrogenase, succinate dehydrogenase,cytochrome bc${}_1$ complex and cytochrome c oxidase.

H${}^{+}$ of NADH${}^{+}$ is transferred from the matrix to the intermembrane space and the electrons are accepted by the first complex NADH dehydrogenase which is further transferred to coenzyme Q which transfers the electron to cytochrome bc${}_1$ complex and finally to cytochrome C which transfers the electron to Cyt-aa3 of complex cytochrome c oxidase.

So, the correct answer is option C.