Ribonucleic acid (RNA) is one of the nucleic acids that contain instructions for carrying out cellular processes. In cells, RNA works with deoxyribonucleic acid (DNA), which contains the organism's genetic information, or genes.

An RNA molecule consists of a chain of phosphate-base-ribose sugar nucleotides. The nucleotide has one of four bases. Two are pyrimidines: cytosine (C) and uracil (U); the other two are purines: adenine (A) and guanine (G). The molecule's composition was defined in the early twentieth century by the American biochemist Phoebus Levene, and its configuration was determined in the 1940s by the British organic chemist Alexander Todd.

RNA was first synthesized in 1955 by the American biochemist Severo Ochoa. In the 1960s, scientists discovered that three consecutive bases, called a triplet or codon, comprise the genetic code or instruction for production of a protein. The American Marshall Nirenberg, Ochoa, and others matched...