Central Dogma of Molecular Biology

The central dogma of molecular biology describes the flow of genetic information within a biological system. It was first stated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970:

The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information. It states that such information cannot be transferred back from protein to either protein or nucleic acid.

Or, as Marshall Nirenberg said, "DNA makes RNA makes protein."

To appreciate the significance of the concept, note that Crick had misapplied the term "dogma" in ignorance. In evolutionary or molecular biological theory, either then or subsequently, Crick's proposal had nothing to do with the correct meaning of "dogma". He subsequently documented this error in his autobiography.

The dogma is a framework for understanding the transfer of sequence information between sequential information-carrying biopolymers, in the most common or general case, in living organisms. There are 3 major classes of such biopolymers: DNA and RNA (both nucleic acids), and protein. There are 3×3 = 9 conceivable direct transfers of information that can occur between these. The dogma classes these into 3 groups of 3: 3 general transfers (believed to occur normally in most cells), 3 special transfers (known to occur, but only under specific conditions in case of some viruses or in a laboratory), and 3 unknown transfers (believed never to occur). The general transfers describe the normal flow of biological information: DNA can be copied to DNA (DNA replication), DNA information can be copied into mRNA (transcription), and proteins can be synthesized using the information in mRNA as a template (translation).