Retroviruses are equipped with which enzyme that allows DNA to be transcribed from an RNA template?

Retroviruses are equipped with which enzyme that allows DNA to be transcribed from an RNA template?

• A. DNA polymerase
• B. RNA polymerase
• C. Ligase
• D. Reverse transcriptase

Answer: (D)

Retroviruses carry an enzyme that makes DNA from an RNA template. This RNA-dependent DNA synthesis is essential because their genome is RNA, and to integrate into the host’s genome they first need a DNA copy. The enzyme that does this is reverse transcriptase, which reads the viral RNA and builds a complementary DNA strand, ultimately forming a double-stranded DNA copy that can be integrated into the host DNA. DNA polymerase would require a DNA template, RNA polymerase would produce RNA from DNA, and ligase only seals breaks in DNA after synthesis. So the ability to convert RNA into DNA is uniquely provided by reverse transcriptase, matching the viral life cycle.

Retroviruses carry an enzyme that makes DNA from an RNA template. This RNA-dependent DNA synthesis is essential because their genome is RNA, and to integrate into the host’s genome they first need a DNA copy. The enzyme that does this is reverse transcriptase, which reads the viral RNA and builds a complementary DNA strand, ultimately forming a double-stranded DNA copy that can be integrated into the host DNA. DNA polymerase would require a DNA template, RNA polymerase would produce RNA from DNA, and ligase only seals breaks in DNA after synthesis. So the ability to convert RNA into DNA is uniquely provided by reverse transcriptase, matching the viral life cycle.