Messenger RNA medicines are basically sets of instructions and these instructions direct cells in the body to make proteins. mRNA plays a key role in human biology and it is a molecule that carries genetic code from DNA in a cell nucleus to ribosomes the protein making machinery of cells. 

Messenger RNA carries the genetic information copied from DNA in the form of three base code words. mRNA is synthesized in the nucleus using the nucleotide sequence of DNA and the process of making mRNA from DNA is called transcription