Not sure if the answer would be either pre-mRNA or exons
In pre-mRNA molecules, they contain introns and exons where: - Introns are the junk codons (they do not code for an amino acid) - Exons are the codons which do code for an amino acid.
In eukaryotic cells, pre-mRNA molecules undergo splicing, which rids of the introns in mRNA molecules, leaving only the exons (the codons which code for proteins), to which a mature mRNA molecule is formed.
