Q6 . What would happen to the mitochondrial proton gradient, mitochondrial respi

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Q6.

What would happen to the mitochondrial proton gradient, mitochondrial respiration (mitochondrial oxygen consumption), and the NADH oxidation rate in cells treated with carbonyl cyanide-4-trifluoromethoxyphenylhydrazone (FCCP), a molecule that increases the permeability of the inner mitochondrial membrane to protons?

Part 1. The mitochondrial proton gradient would:

Select ONE option:

1. increase

2. decrease

Part 2. Mitochondrial respiration (mitochondrial oxygen consumption) would:

Select ONE option:

1. increase

2. decrease

Part 3. The NADH oxidation rate would:

Select ONE option:

1. increase

2. decrease

Q7.

Bongkrekic acid is a mitochondrial toxin produced by bacteria in fermented coconuts. It blocks the inner membrane protein responsible for transporting ATP from the mitochondrial matrix to the cytosol. Bongkrekic acid also inhibits ADP import from the cytosol into the matrix for phosphorylation. Which of the following will occur in a cell exposed to bongkrekic acid?

(Select all that apply.)

A. Most ATP in the cell will be produced by glycolysis because the mitochondria are inhibited.

B. The mitochondrial membrane potential will decrease due to decreased ETC proton pumping.

C. Respiration will decrease because the ATP synthase will lack ADP as the reactant.

D. Mitochondrial ATP levels will decrease.

Q8.

Experiment 1. Two sets of cells are subjected to a FRAP experiment. One cell has a lipid bilayer that includes cholesterol, which makes it less fluid; and the other cell has a membrane made purely of phospholipids. The results are shown below. Which curve, A or B, was obtained from cells with a membrane that includes cholesterol?

Select ONE option:

1. A

2. B

Experiment 2. Membrane fluidity decreases as the temperature cools. If you conducted two FRAP experiments with the same cell, one experiment at warm temperature, and the other at a cooler temperature, which of the FRAP curves below best represents the cell at the warmer temperature?

Select ONE option:

1. A

2. B

Q9.

The release of ATP by the beta subunit is most directly dependent on:

Select ONE option:

1. the flow of protons from the intermembrane space to the matrix.

2. the rotation of the c-ring in the membrane.

3. the passage of electrons along the electron transport chain.

4. a conformational change in the beta subunit.

Q10.

By which of the following mechanisms could ATP synthesis potentially be inhibited?

(Select ALL that apply.)

A. By dissociating the F1 complex from the F0 complex

B. By blocking proton passage through the F0 complex

C. By blocking the rotation of the ?3?3 hexamer of the F1 complex

D. By blocking inorganic phosphate from binding to the F1 complex

Q11.

The following questions ask you to consider what would happen if isolated mitochondria provided with both NADH and oxygen (O2) were treated with agents that prevent the reduction of various components of the ETC. Recall that redox reactions occur sequentially in the electron transport chain. If a certain redox reaction is blocked, all the reactions following it will be blocked as well (much like a traffic jam on a road).

Note that NADH is the only available fuel for the mitochondria in this scenario.

Part 1. Rotenone is a small molecule that prevents NADH from reducing complex I. Which molecule(s) could be reduced if the isolated mitochondria were treated with rotenone?

(Select ALL that apply.)

A. Complex I

B. Complex III

C. Complex IV

D. Coenzyme Q

E. Cytochrome c

F. Oxygen

G. None of the above

Part 2. Antimycin A is a small molecule that inhibits reduction of cytochrome c. Which molecule(s) could be reduced if a cell were treated with antimycin A?

(Select ALL that apply.)

A. Complex I

B. Complex III

C. Complex IV

D. Coenzyme Q

E. Cytochrome c

F. Oxygen

G. None of the above

Part 3. Cyanide (CN-) prevents the reduction of oxygen. Which molecule(s) could be reduced if a cell were treated with cyanide?

(Select ALL that apply.)

A. Complex I

B. Complex III

C. Complex IV

D. Coenzyme Q

E. Cytochrome c

F. Oxygen

G. None of the above

Explanation / Answer

6 part A ) 2 is the correct answer : proton gradient would be decreases because FCCP act as a uncoupler which reduces the proton gradient and so ATP synthesis by increases the inner membrane permeability.

6 part B ) Oxygen consuption decreases because due to the disruption of proton gradient the final electron acceptor is not oxygen here.

6 part C ) NaDH oxidation rate should be increases because FCCP is a uncoupler which only disrupt the proton gradient and ATP synthesis, not deal with NADH oxidation.

7) A, C , D all are apply in this case because membrane potenial not concern with the ATP .

8) B is correct option because B curve slowly recover the photobleach area due to slow movement which shows the presence of cholesterol while A curve rapidly recover all the photobleached area and suddenly recover and saturated.

9) D option: conformational change in the beta subunit to release the ATP

11) part A: Rotenone : inhibit complex 1

11) part B: Antimycine A: inhibit complex 1

11) part A: Cynide : inhibit complex IV and cyt c ( C & E)

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