The central dogma of molecular biology deals with the flow of genetic information within a biological system. It is often stated as "DNA makes RNA, and RNA makes protein",[1] although this is not its original meaning. It was first stated by Francis Crick in 1957,[2][3] then published in 1958:[4][5]
The Central Dogma. This states that once "information" has passed into protein it cannot get out again. In more detail, the transfer of information from nucleic acid to nucleic acid, or from nucleic acid to protein may be possible, but transfer from protein to protein, or from protein to nucleic acid is impossible. Information here means the precise determination of sequence, either of bases in the nucleic acid or of amino acid residues in the protein.
He re-stated it 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."[6]
A second version of the central dogma is popular but incorrect. This is the simplistic DNA → RNA → protein pathway published by James Watson in the first edition of The Molecular Biology of the Gene (1965). Watson's version differs from Crick's because Watson describes a two-step (DNA → RNA and RNA → protein) process as the central dogma.[7] While the dogma as originally stated by Crick remains valid today,[6][8] Watson's version does not.[2]
When Crick enuciated the central dogma, his aim was not to reframe Weismann's division of cells into the somatic line and the germ line, or to defend the modern understanding of evolution by natural selection against the idea of the inheritance of acquired characteristics. The central dogma was based on known or assumed patterns of biochemical information transfer in the cell rather than any dogmatic position. As such it was vulnerable to being invalidated by future discoveries. Nevertheless, in its fundamentals it has been shown to be correct. Real or apparent exceptions to this rule, such as retrotranscription prion disease or transgenerational epigenetic effects have not undermined its basic truth. (p. 263)