RNA serves only as a temporary messenger carrying instructions from DNA to protein.

A simple picture of molecular biology gives RNA one obvious job.

DNA stores the long-term genetic instructions. Messenger RNA, or mRNA, copies part of those instructions and carries them to a ribosome, where the information can be used to make a protein.

That role is real, but RNA turned out to be a much broader class of molecules.

The ribosome itself—the cellular machine that builds proteins—contains large RNA molecules. These ribosomal RNAs are structural parts of the machine and also help carry out the chemical reaction that joins amino acids together.

In the early 1980s, researchers discovered ribozymes: RNA molecules that can catalyze chemical reactions without a protein enzyme doing the chemistry.

Other RNAs regulate genes. Small RNA molecules can recognize matching RNA sequences and help silence them, a process known as RNA interference. Many additional noncoding RNAs help process other RNAs, organize chromosomes, and defend genomes from mobile genetic elements.

RNA can even carry hereditary information directly. Many viruses use RNA rather than DNA as their genome.

Messenger RNA remains one of RNA’s central roles. The correction is to the word “only”: RNA is not merely a temporary courier between DNA and protein.