I thought the whole mRNA thing was bullshit at the beginning, because I know what mRNA is. When DNA is transcribed reading three codons at a time, it produces a strand of nucleotides called mRNA, which then goes on to be read by the ribosome to produce whatever protein was encoded in the section of DNA that it was transcribed from. mRNA, is nothing but a communication 'message' from your DNA to a ribosome, to produce whatever protein it was programed to make.