The complex II of mitochondrial electron transport chain is also known as

The correct answer is Succinate dehydrogenase

Concept:

• The mitochondrial electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons derived from nutrients to oxygen, producing ATP through oxidative phosphorylation.
• Complex II of the ETC is also known as Succinate dehydrogenase. It plays a dual role in both the ETC and the citric acid cycle.
• Unlike other ETC complexes, Complex II does not pump protons across the mitochondrial membrane. Instead, it directly transfers electrons to ubiquinone (coenzyme Q).

Explanation:

• Complex I (NADH dehydrogenase): This complex transfers electrons from NADH to ubiquinone (coenzyme Q), creating ubiquinol and pumping protons into the intermembrane space.
• Complex II (succinate dehydrogenase): This complex oxidizes FADH2 to FAD and transfers electrons to ubiquinone, which is then reduced to ubiquinol.
• Complex III (cytochrome bc1 complex): This complex transfers electrons from reduced ubiquinone (ubiquinol) to cytochrome c, coupled with the translocation of protons across the membrane.
• Complex IV (cytochrome c oxidase): This complex transfers electrons from cytochrome c to oxygen, reducing it to water and helping to pump protons across the membrane.

Fig. ETS.