A message that gets copied, then read aloud
Think of a gene as a written instruction stored safely in a library. The library is your DNA. You never let the original book leave the building — instead, you make a working copy, carry that copy to a workshop, and build something from it. That, in one sentence, is the central dogma of molecular biology: information flows from DNA, to RNA, to protein.
The two big steps have names you will meet again and again. Making the RNA copy from DNA is transcription. Using that RNA copy to build a protein is translation. The copy itself — the one that actually travels to the workshop — is messenger RNA.
Why a copy, and why this direction
Why not build proteins straight from DNA? Because the DNA is precious and must be protected — every cell carries the same master copy and it must last a lifetime. RNA is a cheap, disposable working copy. The cell can make many RNA copies of a busy gene and few of a quiet one, which is one way it controls how much of each protein it makes. We call this overall process gene expression.
The arrows mostly run one way: DNA to RNA to protein, not backward. (Some viruses run one arrow in reverse, copying RNA back into DNA, but the protein never writes itself back into the gene.) The deeper reason the direction matters: the sequence of bases in the gene sets the sequence of amino acids in the protein. Change the order of the letters and you can change the molecule you build. The rest of this track unpacks exactly how those letters get read.
THE CENTRAL DOGMA — one road, two steps
DNA ──transcription──▶ RNA ──translation──▶ PROTEIN
(the master) (the copy) (the worker)
stored in the carries the does the job:
nucleus, kept safe message out enzyme, structure,
signal, etc.
Step 1 transcription : DNA → messenger RNA (copying)
Step 2 translation : mRNA → chain of amino acids (decoding)