Ribonucleic acid
Biological molecule found in almost all of the living organisms, and also some viruses. RNA is a molecule that is chemically similar to DNA and is generally synthesised in cells from a DNA template which it is a copy of. Living cells use DNA in particular as an intermediate genes support to make the proteins they need. RNA can have numerous other functions and particularly intervene in the chemical reactions of the cell. Chemically, RNA is a linear polymer made of a nucleotide chain. Each nucleotide has a phosphate group, a ribose sugar and a nucleobase. Phophodiester bonds bind nucleotides with each other. Four nucleobase are found in RNA : adenine, guanine, cytosine and uracile. Within the cell, RNA is synthesised by transcription of the DNA located in the nucleus.