State the central dogma of molecular biology.

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

Answer: (B)

Genetic information typically flows from DNA to RNA to protein. DNA is transcribed into RNA, and the resulting RNA is translated into a protein. This two-step path explains how genes encoded in DNA ultimately determine the proteins that carry out cellular functions. Some viruses, known as retroviruses, use reverse transcription to convert RNA back into DNA, which can then be used to make more RNA and proteins. But the standard, widely applicable direction is DNA → RNA → Protein, with reverse transcription as an exception in certain viral life cycles.