So basically to see what we mean, let's take a look at the following diagram. So let's suppose this is our precursor mRNA that now contains the polyatail that is shown here and it also contains the five guanosine triphosphate cap. Now, before our pre mRNA actually becomes the mRNA and is able to leave the nucleus, the final process that has to take place is the following. 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.