Ribonucleic acid (RNA) is a molecule similar to DNA. Unlike DNA, RNA is single-stranded. An RNA strand has a backbone made of alternating sugar (ribose) and phosphate groups. Attached to each sugar is one of four bases--adenine (A), uracil (U), cytosine (C), or guanine (G). Different types of RNA exist in the cell: messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). More recently, some small RNAs have been found to be involved in regulating gene expression.


RNA, or ribonucleic acid, is a nucleic acid that is similar in structure to DNA but different in subtle ways. The cell uses RNA for a number of different tasks, one of which is called messenger RNA, or mRNA. And that is the nucleic acid information molecule that transfers information from the genome into proteins by translation. Another form of RNA is tRNA, or transfer RNA, and these are non-protein encoding RNA molecules that physically carry amino acids to the translation site that allows them to be assembled into chains of proteins in the process of translation.

- Leslie G. Biesecker, M.D.