Information RNA, composition, structure and function.

Ribonucleic acid (RNA) is a ubiquitous family of large biological molecules that perform multiple vital roles in the coding, decoding, regulation, andexpression of genes. Together with DNA, RNA comprises the nucleic acids, which, along with proteins, constitute the three major macromoleculesessential for all known forms of life. Like DNA, RNA is assembled as a chain of nucleotides, but is usually single-stranded. Cellular organisms usemessenger RNA (mRNA) to convey genetic information (often notated using the letters G, A, U, and C for the nucleotides guanine, adenine, uracil andcytosine) that directs synthesis of specific proteins, while many viruses encode their genetic information using an RNA genome.

Messenger RNA (mRNA) is a large family of RNA molecules that convey genetic information from DNA to the ribosome, where they specify the amino acid sequence of the protein products of gene expression. Following transcription of primary transcript mRNA (pre-mRNA) by RNA polymerase, processed, mature mRNA is translated into a polymer of amino acids: a protein, as summarized in thecentral dogma of molecular biology.

As in DNA, mRNA genetic information is encoded in the sequence of nucleotides, which are arranged into codons consisting of threebases each. Each codon encodes for a specific amino acid, except the stop codons, which terminate protein synthesis. This process of translation of codons into amino acids requires two other types of RNA: Transfer RNA (tRNA), that mediates recognition of the codon and provides the corresponding amino acid, and ribosomal RNA (rRNA), that is the central component of the ribosome's protein-manufacturing machinery.

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