Which statement best describes the central dogma with exceptions?

Which statement best describes the central dogma with exceptions?

• A. DNA -> RNA -> Protein (with reverse transcription in some viruses).
• B. RNA -> DNA -> Protein (in some viruses).
• C. DNA -> Protein -> RNA.
• D. Protein -> RNA -> DNA.

Answer: (A)

The central idea being tested is how genetic information normally flows in biology. In cells, information goes from DNA to RNA and then to protein. This happens because DNA is transcribed into messenger RNA, and the ribosome then translates that RNA into a polypeptide chain, which folds into a functional protein. The statement that best describes this flow with the notable exception is the standard DNA -> RNA -> Protein path, plus reverse transcription in some viruses. In those viruses, the RNA genome is reverse-transcribed into DNA by an enzyme called reverse transcriptase, and the resulting DNA can be integrated into the host genome. From there, the host’s transcription and the usual translation machinery produce RNA and then proteins. This captures both the normal direction of information flow and the well-known exception. Other directional options would imply information moving in an order that doesn’t reflect how transcription and translation work in cells, or ignore the well-documented reverse transcription process seen in retroviruses.

The central idea being tested is how genetic information normally flows in biology. In cells, information goes from DNA to RNA and then to protein. This happens because DNA is transcribed into messenger RNA, and the ribosome then translates that RNA into a polypeptide chain, which folds into a functional protein.

The statement that best describes this flow with the notable exception is the standard DNA -> RNA -> Protein path, plus reverse transcription in some viruses. In those viruses, the RNA genome is reverse-transcribed into DNA by an enzyme called reverse transcriptase, and the resulting DNA can be integrated into the host genome. From there, the host’s transcription and the usual translation machinery produce RNA and then proteins. This captures both the normal direction of information flow and the well-known exception.

Other directional options would imply information moving in an order that doesn’t reflect how transcription and translation work in cells, or ignore the well-documented reverse transcription process seen in retroviruses.