The Electron Transport Chain: Complex III

The video tutorial explains the physiology and mechanism of Complex III in the mitochondrial respiratory chain. It covers the enzyme's various names, its role in electron transfer from ubiquinol to cytochrome C, and the Q cycle. The tutorial also discusses the enzyme's ability to pump protons across the membrane, contributing to the proton gradient. The net reaction involves the transfer of electrons from ubiquinol to cytochrome C, which then moves to cytochrome C oxidase.

What is another name for Complex III in the mitochondrial respiratory chain?

• Cytochrome C dehydrogenase

• Cytochrome C synthase

• Cytochrome C reductase

• Cytochrome C oxidase

What is the role of ubiquinol in the Q cycle?

• It acts as a proton donor.

• It serves as an electron donor.

• It acts as a substrate for ATP synthesis.

• It functions as a coenzyme.

Why is ubiquinol able to move through the mitochondrial membrane?

• It is a protein.

• It is hydrophobic.

• It is charged.

• It is hydrophilic.

What is the significance of the iron-sulfur centers in cytochrome C reductase?

• They bind oxygen molecules.

• They transfer electrons.

• They synthesize ATP.

• They pump protons.

How many electrons can cytochrome C accept at a time?

• Four

• Three

• Two

• One

What is the net result of the Q cycle in terms of ubiquinol?

• Three ubiquinol molecules are produced.

• No ubiquinol molecules are used.

• One ubiquinol molecule is regenerated.

• Two ubiquinol molecules are consumed.

How many protons are pumped across the membrane by Complex III?

• Two

• Three

• Four

• Five