In this video, we're going to begin our lesson on the steps of transcription. The process of transcription consists of initiation of transcription, then elongation of transcription, and the third and final step is the termination of transcription. We're going to talk about each of these three steps of transcription in their own separate video, starting with initiation.
The initiation of transcription refers to the beginning of transcription. This involves the RNA polymerase binding to the promoter region on the DNA and separating the two strands of DNA. When those two strands of DNA are separated, it allows the second step of transcription to begin. It turns out that transcription in eukaryotes and prokaryotes is a little bit different. In prokaryotes, the RNA polymerase, which is the main enzyme involved in transcription, binds to the promoter region on its own. However, in eukaryotes, transcription factor proteins are required for the RNA polymerase to bind to the promoter.
The unwinding of the DNA by the RNA polymerase exposes the DNA template strand, which the RNA polymerase uses as a guide to build the RNA. If we take a look at our image, you'll notice on the left-hand side, we're showing you the initiation of transcription in prokaryotes, and on the right-hand side, the initiation of transcription in eukaryotes. In the initiation phase, we know that the RNA polymerase binds to the promoter and separates the two strands of DNA. Here in our image, the pink circle represents the RNA polymerase binding specifically to the promoter region on the DNA.
It will then unwind the DNA, separating the two strands and exposing the template strand of the DNA. Downstream, you can also see the terminator, which is involved in the final process of transcription. On the right-hand side, you'll see the same process, initiation of transcription for eukaryotes. The main difference we're focusing on here is that in eukaryotes, the RNA polymerase requires transcription factor proteins, represented here as yellow shapes, to bind to the promoter.
In eukaryotes, the background shows the bound transcription factors that help recruit the RNA polymerase so that it can also bind to the promoter. Transcription initiation allows for the second step of transcription to begin, which is elongation. We'll talk more about elongation, the second step of transcription, in our next video. I'll see you all there.