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Group VI viruses such as HIV carry diploid ssRNA genomes. How is that genome handled in the host cell?
AReverse transcribed to dsDNA, then integrated
BTranslated straight away by host ribosomes
CCut into segments and packaged separately
DCopied only by a viral RNA polymerase
Answer & Solution
Correct answer: A. Reverse transcribed to dsDNA, then integrated
1. A group VI virus carries two copies of a single-stranded RNA genome, which is what diploid means here.
2. The enzyme reverse transcriptase converts that RNA into double-stranded DNA.
3. The double-stranded DNA is then carried to the nucleus of the host cell.
4. There it is inserted into the host genome.
5. Messenger RNA is afterwards produced by transcription of that integrated viral DNA.
6. A viral RNA polymerase alone would describe group III or group V, so that option lands in the wrong group.
7. Segmented packaging describes influenza rather than a Baltimore group, so it is a distractor.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 21 "Viruses", section 21.1 Viral Evolution, Morphology, and Classification_
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