central dogma

The central dogma is the big-picture summary of how genetic information flows through a cell: DNA is transcribed into RNA, and RNA is translated into protein. Think of it as the master pipeline — instructions stored in DNA are copied into a working message, and the message is built into a functional protein.

It was framed by Francis Crick in 1958 to make a specific claim: once information has passed into protein, it cannot flow back out to nucleic acids. In other words, sequence information moves from genes to proteins, never the reverse. Proteins do not rewrite the genes that made them.

The dogma is a framework, not an absolute law of one-way traffic. Some viruses run RNA back into DNA using reverse transcriptase, and RNA can be copied into RNA. These were not violations of Crick's actual statement (which concerned protein-to-nucleic-acid flow), but they did broaden the textbook arrows beyond the simplest DNA-to-RNA-to-protein picture.