Recently I was reading about Molecular genetics. In which that is Do the stop codons which is present in mRNA come from DNA by transcription or it is attached after transcription.

  • $\begingroup$ All codons, whether start, stop, or regular amino acid-encoding, are encoded in DNA. The only thing added to mRNA is the poly-A tail. $\endgroup$ – MattDMo Sep 17 at 0:01