State the central dogma of molecular biology and name a common exception.

State the central dogma of molecular biology and name a common exception.

• A. DNA is transcribed into RNA, which is translated into protein; a common exception is reverse transcription (RNA to DNA) in retroviruses.
• B. Protein is transcribed to DNA and then to RNA; exceptions include transcription to lipids.
• C. RNA is transcribed into DNA and then into protein; exceptions include RNA to RNA replication without translation.
• D. DNA makes proteins directly without RNA; exception is RNA transcription.

Answer: (A)

At its core, genetic information flows from DNA to RNA to protein. DNA is transcribed into messenger RNA, and the ribosome translates that RNA into a protein. A common exception is reverse transcription in retroviruses, such as HIV. These viruses carry their genome as RNA and use reverse transcriptase to synthesize a DNA copy from the RNA template. That DNA can integrate into the host genome and then be transcribed and translated, momentarily reversing the usual direction. This keeps the overall idea intact—the information ultimately governs protein production—but it shows that RNA can be copied into DNA as part of the replication cycle.

At its core, genetic information flows from DNA to RNA to protein. DNA is transcribed into messenger RNA, and the ribosome translates that RNA into a protein. A common exception is reverse transcription in retroviruses, such as HIV. These viruses carry their genome as RNA and use reverse transcriptase to synthesize a DNA copy from the RNA template. That DNA can integrate into the host genome and then be transcribed and translated, momentarily reversing the usual direction. This keeps the overall idea intact—the information ultimately governs protein production—but it shows that RNA can be copied into DNA as part of the replication cycle.