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. So it also should contain our polyatail. So once all these processes actually take place, once we add the five cap, once we add our tail that contains the polyadeny nucleotides, and once we splice together the exons and remove the introns, only then does our pre mRNA molecule become the mRNA molecule. And only then can the messenger RNA actually exit the nucleus into the cytoplasm and undergo protein synthesis and be used by the ribosomes to synthesize our proteins.