In 1957, three years after his Nobel-winning work on the structure of DNA, Francis Crick proposed what he provocatively called the Central Dogma of molecular biology: DNA is transcribed into RNA, and RNA is translated into protein, and information does not flow back from protein to nucleic acid. The genetic code goes one way. The dogma turned out to be approximately true, with important exceptions, and remains the organizing skeleton of molecular biology nearly seventy years later.
The mechanism is one of the great miracles of biological evolution. DNA stores hereditary information in a double-helical sequence of four bases. RNA (specifically messenger RNA) is transcribed from DNA by RNA polymerase, carrying a single-stranded copy out of the nucleus. Ribosomes read the mRNA in three-letter codons (each specifying one amino acid) and assemble proteins — the working molecules of the cell — by linking amino acids in the specified order. The exceptions to one-way flow are now well-characterized: retroviruses (including HIV) reverse-transcribe RNA back into DNA (David Baltimore and Howard Temin, 1970, Nobel 1975); prions propagate by protein-to-protein conformational change without nucleic-acid involvement; epigenetics allows heritable phenotypic changes through DNA methylation and histone modification rather than sequence change. The central dogma has been the framework underneath every twentieth- and twenty-first-century molecular biology breakthrough: gene cloning, polymerase chain reaction, recombinant DNA, the Human Genome Project, RNA interference, CRISPR-Cas9, mRNA vaccines, and the recent revolution in protein-structure prediction (AlphaFold).
mRNA vaccines (Pfizer-BioNTech, Moderna) — perhaps the most important medical technology of the 2020s — work by delivering RNA directly to cells and letting the cell's own protein-synthesis machinery produce the antigen. The technology was enabled by decades of central-dogma research and is now being applied to cancer immunotherapy, rare diseases, and additional infectious diseases. CRISPR edits DNA itself; gene therapy introduces new DNA into patients' cells; AlphaFold predicts the protein conformation that DNA sequences will produce. The dogma is no longer just a description of how cells work — it is also a programming language we are learning to write.