Question

Which among the following membrane bound complexes in mitochondria is not a proton pump?

• A. Cytochrome b and c
• B. Cytochrome c oxidase
• C. $\mathrm{NADH}$ dehydrogenase
• D. Succinate dehydrogenase

Answer 1

The correct option is D Succinate dehydrogenase

A proton pump is an integral membrane protein pump that builds up a proton gradient across a biological membrane.

In mitochondria, the electron transport complexes I ($\mathrm{NADH}$ dehydrogenase), III (cytochrome ${\mathrm{bc}}_1$ complex), IV (cytochrome c oxidase) and V ($\mathrm{ATP}$ synthase) are proton pumps driven by electron transport but complex II which consists of succinate dehydrogenase is not a proton pump.