Kaplan Full Length 2 Bio #144

[silkworm]

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This question is about viral RNA transcription in HIV-infected cell. It asks about which nucleotide is NOT needed for the transcription, giving the choice of A, T, G, U.

I thought in reverse transcription, since you are making DNA, you would need T, so I picked U. But apparently this is not the case, the correct answer is T. So in this case, should I have assumed the viral RNA is making a RNA copy? I always thought HIV RNA would reverse transcribe to make DNA to integrate into the genome, and the passage said as much.

Can anyone shed light on this?

 

[willthatsall]

The question says the researcher is studying the process by which viral mRNA is transcribed in an HIV-infected cell. It's not asking about the process from which DNA is transcribed from the RNA genome. Do you see the difference?

 

[silkworm]

Yes, but I assumed they are talking about mRNA ---> DNA reverse transcription.

So in this situation, the viral mRNA must first make another mRNA before integrating into genome?

 

[premedgeek]

some of the kaplan's questions are worded very ambigiously.

 

[willthatsall]

Yes, but I assumed they are talking about mRNA ---> DNA reverse transcription.

So in this situation, the viral mRNA must first make another mRNA before integrating into genome?

Yeah, I see how you could think that since you know that HIV is a retro virus, but it just doesn't have anything to do with the question. In the case you are thinking of, mRNA is not being transcribed. Also, keep in mind that the viral RNA genome is not the same thing as mRNA, although some viral RNA genomes contain mRNA that codes for RNA replicase. So reverse transcriptase does not transcribe DNA from mRNA, it transcribes DNA from the viral genome.