Ribonucleic acid

Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulating , and expressing genes. RNA and DNA are nucleic acids, which, along with lipids, proteins and carbohydrates, constitute the four 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 convey genetic information with messenger RNA (mRNA), which uses sequencing of of base-pairs of nitrogenous bases—guanine, uracil, adenine, and cytosine)—to direct the syntheses of specific proteins. Many viruses encode their genetic information using an RNA genome.

Some RNA molecules play an active role within cells by catalyzing biological reactions, controlling gene expression, or sensing and communicating responses to cellular signals. One of these active processes is protein synthesis, a universal function where RNA molecules direct the assembly of proteins on ribosomes. This process uses transfer RNA (tRNA) molecules to deliver amino acids to the ribosome, where ribosomal RNA (rRNA) then links amino acids together to form proteins.

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