Central Dogma of Molecular Biology

The central dogma of molecular biology, stated by Francis Crick in 1957 and published in 1958, holds that genetic information flows in one direction only, from DNA to RNA to protein, and never back out of a protein into nucleic acid. Crick's original claim was narrower than the later shorthand DNA makes RNA, and RNA makes protein: it said only that once information has passed into a protein's sequence it cannot get out again, leaving open other transfers among nucleic acids that were confirmed later, such as RNA being copied back into DNA. The idea gave the double helix's chemistry a functional direction, explaining how the sequence read from Watson and Crick's structure becomes the sequence of a working protein.