Biochemistry : Other Electron Transport Chain Concepts

Study concepts, example questions & explanations for Biochemistry

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Example Questions

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Example Question #11 : Other Electron Transport Chain Concepts

Reactive oxygen species are by-products of the electron transport chain. Which of the following are considered reactive oxygen species?

Possible Answers:

Hydroxyl radical 

Superoxide 

Hydrogen peroxide 

None of these

All of these

Correct answer:

All of these

Explanation:

Reactive oxygen species are superoxide, hydrogen peroxide, and hydrogen radicals. They are degraded by catalase, superoxide dismutase, and glutathione peroxidase. Neutrophils use reactive oxygen species to kill bacteria during the phagocytic oxidative burst. 

Example Question #12 : Other Electron Transport Chain Concepts

Which of the following are uncouplers of the electron transport chain?

I. Carbon monoxide

II. 2,4-Dinitrophenol

III. Nitric oxide 

IV. Aspirin

Possible Answers:

I and II

I and III

I, III, and IV

II and IV

I and IV

Correct answer:

II and IV

Explanation:

Uncouplers of the electron transport chain decrease the proton gradient and thus decrease ATP synthesis. Most energy from the electron transport chain is released as heat. The most common uncouplers are 2,4-dinitrophenol and aspirin, as well as thermogenin. Carbon monoxide is an inhibitor of the electron transport chain, not an uncoupler. Nitric oxide does not affect directly the electron transport chain.

Example Question #13 : Other Electron Transport Chain Concepts

What is an electron acceptor in oxidative phosporylation?

Possible Answers:

Carbon monoxide

NADH

Oxygen

ATP

Carbon dioxide

Correct answer:

Oxygen

Explanation:

Oxygen is an electron acceptor. In the absence of oxygen (hypoxia) cells cannot generate ATP in the mitochondria. Instead, they will utilize glycolysis. Oxygen is required to carry out the electron transport chain and produce ATP via oxidative phosphorylation.

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