what is mrna
MRNA. Definition. noun. Abbreviated form for messenger ribonucleic acid, the type of RNA that codes for the chemical blueprint for a protein (during protein synthesis). Supplement. In prokaryotes, mRNA is produced by splicing a large primary transcript from a DNA sequence. The mRNAs of prokaryotes are usually very short lived (from seconds to more than an hour) and protein synthesis starts even while the mRNA is still being synthesized.