Q3. Your lab has recently identified a small molecule present in e-cigarette vap
ID: 261763 • Letter: Q
Question
Q3.
Your lab has recently identified a small molecule present in e-cigarette vapor called TX32. You suspect it may be toxic and want to test its effects on mitochondrial function and membrane potential more specifically.
You prepare four dishes with cells. You treat the cells with three different doses of TX32 and leave one untreated for comparison (Figure A).
The following day, you add a small amount of TMR for 1 hour (Figure B) and use a fluorescence microscope to measure the TMR signal in each dish (Figure C).
Figure A. Dishes of treated and untreated cells.
Figure B. Addition of TMR to each cell culture dish.
Figure C. Example of TMR signal in a cell.
Membrane Potential Experiment
1 point possible (graded)
You observe a significant decrease in TMR signal in TX32-treated cells that varies by dose (Figure A). How might TX32 affect membrane potential?
Figure A. TMR signal in treated and untreated cells.
Select ONE option:
1. Directly inhibits ETC proton pumping activity like rotenone or antimycin.
2. Interfere with glucose metabolism and/or TCA cycle and thereby reduce NADH and FADH2 supply to ETC
3. Increase the proton leak through the membrane like FCCP.
4. All of the above.
Untreated TX32 Low Dose TX32 Medium Dose TX32 High DoseExplanation / Answer
Please find the answers below:
Answer A: According to the graphical data, it can be clearly seen that the compound is preventing ETC to take place even at low dosage. This means that this compound has direct effect on proton pumping across the mitochondrial membrane or the electron transport across various complexes or both.
Answer 2: Choice 4
Reason: As it can be seen that the compound is able to destruct ETC even at low dosage, it is very likely that it poisons the mitochondria by depriving it of the proton-motive force and electron transport. Further, the supply of initial substrate to the ETC might also have been interrupted due to faulty citric acid cycle and hence lack of energy driving tendency of the mitochondria.
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