Messenger RNA (mRNA), molecule in cells that carries codes from the DNA in the nucleus to the sites of proteinsynthesis in the cytoplasm (the ribosomes). The molecule that would eventually become known as mRNA was first described in 1956 by scientists Elliot Volkin and Lazarus Astrachan. In addition to mRNA, there are two other major types of RNA: ribosomal RNA(rRNA) and transfer RNA (tRNA)…read more.