Now on top of essentially removing the introns these mRNA molecules in our cells and other eukaryotic cells are modified in two other ways. We basically cap the beginning with a special type of nucleotide sequence and that's called the capping process. And at the end of that mRNA we add an additional sequence that consists of a polyadenosine nucleotides as shown in the following diagram and we'll discuss what that means and what that is used for in more detail in a future lecture. In this lecture we're simply going to introduce the fact that in prokaryotic cells we don't have this process taking place but in eukaryotic cells we do have the process of mrname modification. So as soon as we synthesize that particular mRNA that mRNA is known as the primary mRNA, the precursor mRNA or the pre mRNA molecule. And it consists of these introns shown in green and the exons shown in blue.