What does the Central Dogma of Molecular Biology describe?

• A. DNA → RNA → Protein
• B. Protein → DNA → RNA
• C. RNA → DNA → Protein
• D. DNA → Protein → RNA

Answer: (A)

Information in living cells flows from DNA to RNA to protein. DNA is transcribed into messenger RNA, and the mRNA is then translated into a protein, so the sequence is DNA → RNA → protein. This path is how genetic information is used to make functional molecules. Other orders would imply incorrect directions of information flow—for example, proteins directing DNA or RNA, or transcription skipping the RNA step—so they don’t describe the normal process. There are exceptions, such as retroviruses that reverse transcribe RNA into DNA, but those are not the usual direction described here.