Retroviruses carry an enzyme called _____, which allows them to convert their RNA into complementary DNA.

Retroviruses carry an enzyme called _____, which allows them to convert their RNA into complementary DNA.

• A. DNA Polymerase
• B. Helicase
• C. Ligase
• D. Reverse Transcriptase

Answer: (D)

Retroviruses carry an enzyme that can copy their RNA into DNA, because their genome is RNA and needs to be converted to DNA to integrate into the host genome. This enzyme, reverse transcriptase, is an RNA-dependent DNA polymerase: it uses RNA as a template to synthesize complementary DNA. The resulting cDNA can then be integrated into the host DNA by another viral enzyme. The other enzymes listed don’t perform this RNA-to-DNA transcription: DNA polymerase works on DNA templates, helicase unwinds DNA, and ligase seals DNA breaks. That’s why reverse transcriptase is the correct choice.

Retroviruses carry an enzyme that can copy their RNA into DNA, because their genome is RNA and needs to be converted to DNA to integrate into the host genome. This enzyme, reverse transcriptase, is an RNA-dependent DNA polymerase: it uses RNA as a template to synthesize complementary DNA. The resulting cDNA can then be integrated into the host DNA by another viral enzyme. The other enzymes listed don’t perform this RNA-to-DNA transcription: DNA polymerase works on DNA templates, helicase unwinds DNA, and ligase seals DNA breaks. That’s why reverse transcriptase is the correct choice.