Explain the post-transcriptional changes that occur in mRNA before translation.

After DNA has been transcribed into mRNA but before is it is translated into it's polypeptide amino acid chain, post-transcriptional changes take place.DNA, and therefore its corresponding mRNA are made up of segments called exons and introns.Exons are the segments that will go on to be translated by the ribosome and form the final protein structure.Introns are the non-coding segments that are excised (cut out) of the mRNA sequence and discarded before it goes on to be translated by the ribosome.Once the mRNA strand has been formed but before post-transcriptional changes, mRNA is sometimes called immature or pre-mRNA.Post-transcriptional changes take place so that one strand of DNA can go on to form many different combinations of mRNA before they are translated into proteins.