DNA is a nucleic store of genetic information in eukaryotes. It consists of a combination of four different nucleobases; adenine, cytosine, guanine and thymine (abbreviated to A, C, G and T respectively). Some parts of DNA are known as genes and code for a specific protien. Genes are made up of triplets of nucleobases known as codons, each of which codes for one amino acid in the protein product. The first step in protien synthesis is transcription. The desired gene is transcribed into a messenger RNA (mRNA) molecule inside the nucleus of the cell by means of enzyme activity. RNA is similar to DNA but it uses the base Uracil (U) in place of Thymine (T) and it has a slightly different structure to its backbone. The mRNA molecule is then moved out of the nucleus to the ribosomes on the rough endoplasmic reticulum to be translated into protien. Transfer RNA (tRNA) molecules then match up each codon with an amino acid and enzymes bind the string of amino acids together into the desired protein. The protein product is then free to perform the function it was made for.