So when this reaches this region basically the RNA polymerase combines with this initiation factor with these proteins and it's the RNA polymerase itself that actually unwinds these two molecules, unwinds the two single stranded DNA molecules and creates a bubble that is known as the transcription bubble and we'll discuss that in detail in just a moment. So basically one important difference between DNA polymerase and RNA polymerase is that DNA polymerase itself cannot actually unwind the double helix of our DNA but the RNA molecule, the RNA polymerase can in fact itself unwind our molecule. Recall that in our discussion on DNA replication a special type of enzyme known as DNA helicase actually has to unwind the double helix. But in this case the RNA polymerase itself can actually unwind our double helix. So this concludes our discussion of initiation. Let's move on to the process of elongation.