A _____ is a virus that stores its genetic material as RNA; therefore, they infect host cells with RNA.

A _____ is a virus that stores its genetic material as RNA; therefore, they infect host cells with RNA.

• A. Bacteriophage
• B. Endovirus
• C. Retrovirus
• D. DNA virus

Answer: (C)

RNA genomes that rely on reverse transcription show a distinct replication strategy: retroviruses carry reverse transcriptase to convert their RNA into DNA once inside a host cell, and this DNA integrates into the host genome. From that integrated provirus, the host’s transcription machinery makes viral RNAs and mRNAs, leading to production of new viral particles. This combination of an RNA genome and the need to reverse-transcribe into DNA before integration sets retroviruses apart from DNA viruses, which carry DNA genomes, and from bacteriophages that typically infect bacteria and usually have DNA genomes. HIV is a classic example of this kind of virus.

RNA genomes that rely on reverse transcription show a distinct replication strategy: retroviruses carry reverse transcriptase to convert their RNA into DNA once inside a host cell, and this DNA integrates into the host genome. From that integrated provirus, the host’s transcription machinery makes viral RNAs and mRNAs, leading to production of new viral particles. This combination of an RNA genome and the need to reverse-transcribe into DNA before integration sets retroviruses apart from DNA viruses, which carry DNA genomes, and from bacteriophages that typically infect bacteria and usually have DNA genomes. HIV is a classic example of this kind of virus.