MCAT® ExamBiological and Biochemical Foundations of Living SystemsEasy
A research team is investigating a novel antiviral drug that specifically inhibits the enzyme responsible for synthesizing DNA from an RNA template. This drug would be most effective against which type of virus?
- ARetroviruses
- BBacteriophages
- CDNA viruses that replicate in the nucleus
- DRNA viruses that use RNA-dependent RNA polymerase
Show answer & explanationAnswer & explanation
Correct answer: A. Retroviruses
The enzyme responsible for synthesizing DNA from an RNA template is reverse transcriptase. Retroviruses, such as HIV, are unique in their life cycle because they use reverse transcriptase to convert their RNA genome into DNA, which then integrates into the host cell's genome. Therefore, a drug inhibiting this enzyme would specifically target retroviruses.
Why the other options are wrong
- B. Bacteriophages are viruses that infect bacteria; their replication mechanism varies but typically does not involve reverse transcriptase in this manner.
- C. DNA viruses replicate DNA from a DNA template, not RNA.
- D. RNA viruses using RNA-dependent RNA polymerase synthesize RNA from an RNA template, not DNA from RNA.
Reverse Transcriptase Function
Reverse transcriptase is an enzyme that catalyzes the synthesis of DNA from an RNA template, a process known as reverse transcription. It is characteristic of retroviruses.
- Synthesizes DNA from an RNA template
- Essential for retroviral replication (e.g., HIV)
- A target for antiviral drugs
- Discovered in 1970
Memory trick: Reverse Transcripts make DNA from RNA.