Well, let's take a look at the following seven steps that basically describes how we can produce this double stranded complementary DNA molecule. So we basically take our eukaryotic cell and we extract that modified mRNA molecule. And so this blue molecule is that modified mRNA molecule. It contains the five prime cap and the polyatail on the three prime N and it only contains the exons, it does not contain the introns. Now, before we can actually add reverse transcriptase into the mixture, we have to create a DNA primer and we have to attach that DNA primer onto the three prime end of that mRNA molecule. Now, because all mRNA molecules in eukaryotic cells are modified with a polyatail, what that means is it's pretty easy to produce that DNA primer that is complementary to the polyatail.