Ribonucleic acid (
RNA) is a
polymeric molecule implicated in various biological roles in
coding,
decoding,
regulation, and
expression of
genes. RNA and
DNA are
nucleic acids, and, along with
proteins and
carbohydrates, constitute the three major
macromolecules essential for all known forms of
life. Like DNA, RNA is assembled as a chain of
nucleotides, but unlike DNA it is more often found in nature as a single-strand folded onto itself, rather than a paired double-strand. Cellular organisms use
messenger RNA (mRNA) to convey genetic information (using the letters G, U, A, and C to denote the nitrogenous bases
guanine,
uracil,
adenine, and
cytosine) that directs synthesis of specific proteins. Many
viruses encode their genetic information using an RNA
genome.
