Cytochrome c Ubiquinol Oxidoreductase

The video provides an in-depth look at Complex III in the respiratory chain, focusing on the cytochrome C ubiquinol oxidoreductase and its mechanism, the Q cycle. It explains the electron pathways, the regeneration of ubiquinol, and the role of cytochrome C, including its involvement in apoptosis.

What is the primary function of Complex III in the respiratory chain?

• To synthesize ATP directly

• To transfer electrons from ubiquinol to cytochrome C

• To pump protons across the mitochondrial membrane

• To oxidize NADH to NAD+

In the Q cycle, what happens to the electrons from ubiquinol?

• They are split and follow different pathways

• They are combined into a single electron

• They are used to directly produce ATP

• They are stored in the mitochondrial matrix

Which component in the Q cycle accepts electrons from the iron-sulfur center?

• Heme C1

• Heme B low potential

• Ubiquinone

• Cytochrome C

What is regenerated during the Q cycle that is crucial for its continuation?

• FADH2

• Ubiquinol

• NADH

• ATP

How many electrons can cytochrome C accept at a time?

• Two

• Three

• One

• Four

What is the role of cytochrome C in the electron transport chain?

• It acts as a proton pump

• It transfers electrons between Complex III and IV

• It synthesizes ATP

• It oxidizes NADH

Why is cytochrome C unique among the components of the electron transport chain?

• It is the only membrane-bound enzyme

• It is the only soluble enzyme

• It directly produces ATP

• It is not involved in electron transfer

What additional role does cytochrome C play outside of the electron transport chain?

• It acts as a hormone

• It is involved in apoptosis

• It synthesizes glucose

• It stores energy

What is the significance of the Q cycle in the context of the electron transport chain?

• It reduces cytochrome C and regenerates ubiquinol

• It oxidizes NADH

• It pumps protons into the mitochondrial matrix

• It directly produces ATP

Which of the following is NOT a function of Complex III?

• Synthesizing ATP

• Pumping protons across the membrane

• Regenerating ubiquinol

• Reducing cytochrome C