So, the molecule contains sections known as exons. And these are the sections that actually carry the genetic code that codes for our protein. It also contains these introns which are sections that do not code for any type of protein. So what must take place in the nucleus is a certain set of proteins known as the splicosome has to remove these introns and basically splice together or combine our exons. So these three sections are removed and we basically splice together these four exon sections including the polyatail. And so we form the following molecule as shown.