<P> 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 . RNA polymerase transcribes primary transcript mRNA (known as pre-mRNA) into processed, mature mRNA . This mature mRNA is then translated into a polymer of amino acids: a protein, as summarized in the central dogma of molecular biology . </P> <P> As in DNA, mRNA genetic information is in the sequence of nucleotides, which are arranged into codons consisting of three base pairs 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 . </P>

The m in mrna stands for messenger. why is this molecule called messenger rna