Overview of Transcription

by Jason Amores Sumpter
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in this video, we're going to do an overview of the entire process of transcription. However, it's important to keep in mind that as we continue to move forward in our course, we're going to continue to break down transcription and more details. And later in our course, in a separate video, we'll talk about the individual steps of transcription and more details. And here in this video, we're just doing an overview of the entire process. And so it's important to note that the two strands of DNA in a gene are referred to as either the coding strand or the template strand. Now turns out that during transcription, uh, the RNA molecules that are being built are going to have the same exact sequence as the coding DNA strand. And the template DNA strand is just going to serve as a template for building the RNA. But ultimately, the RNA molecules gonna be carrying the message that's in the coding DNA strand. And so the only difference between the RNA sequence and the coding DNA sequence is going to be the fact that it's going to be replacing all of the tees or thigh means with use or your cells and recall. That is because Arna has your cells, whereas DNA is going tohave fi means, and we'll be able to see an example an application of this down below in our example. Now it's also important to note that during transcription, the RNA molecule itself is going to be built from its five prime end to its three prime end. And it's going to be built by pairing free our DNA nucleotides, that air floating around in the cell on a DNA template. And so we'll be able to see that down below in our image over here on this side. Now this nucleotide pairing is going to occur via Watson and Crick base pairing, which recall we already covered in our previous lesson videos, which basically says that Azour Adnan's will pair with teas or thigh means. Or, in the case of DNA base pairing with Arna A's are going to be pace pairing with use because remember that Arna use are going to replace the teas. And then, of course, we know that geez are going to base pair with sees, and so if we take a look at our image down below, we can better understand the overall overview of transcription. And so this example here wants us to determine the sequence for the template DNA strand and for the mRNA transcript, given the following coding Strand. And so when we take a look at this side of the image over here, which will notice is we have a DNA molecule and recall that DNA has two strands and each of these two strands one of them is going to be the coding strand, and the other one is going to be the template strand. Uh, in this case, the coding strand is at the top here. And the, uh, template strand is the one on the bottom. And so it wants us to determine the template DNA strand sequence along with the Marna Transcript sequence that's down below. And so what's important to note here is that when we look at the coding sequence coding strand sequence, it is G A T. C. And we know that through Watson and Crick base pairing that the GSR going to base pair was sees. And so these GS here will base pair with sees on the DNA. So we know that Cesaire going to go in these positions and the A's air going to base pair with tees in the DNA. And so we will put tease here and tease Will base pair with ace and, of course, sees base pair with jeez. And so this sequence here is the sequence of the template strand sequence. Now, of course, the process of transcription represented by this arrow is going to use the DNA to build our DNA. And the DNA, as we mentioned up above, are going to have the same sequence as the coding DNA strand with this exception right here, replacing the teas with use. And so what we can see here is that the coding sequence strand is right here at the top in our DNA is going to have the same sequence as the coding strand. So it is going to be G a. And then, of course, replacing the teas with use as we mentioned here, replacing the teas with use. And so here, instead of having a tea at this position, we're going to have a you And then, of course, the sea here is going to go right here. And so this will be the sequence of the RNA. Now it turns out that in Eukaryotic cells, the Arna that is first made is called a pre m r n a transcript because it's not fully mature. But we're going to talk more details about that later in our course. Now, over here on the right were kind of showing ume or of uh so ah, zoom out of the overall process of transcription and recall that they are in a prelim Aries enzyme, which is this big pink circle. In the background is the primary enzyme involved with transcription, and so it will bind to the promoter region on a gene and start to transcribe the gene. And so when it transcribes the gene it's going to be building the RNA in the RNA is gonna be built from its five prime into its three prime end again by pairing free RNA nucleotides, that air floating around in the self on a DNA template. And so you can see that this RNA is being built from its five prime end over here towards its three prime and over here, and the direction of the RNA polymerase is to the right, so transcription is proceeding to the right And so what you'll notice is that the DNA is going to unwind, and you could see that there is a coding strand and again, a template strand. And the RNA, of course, is going to end up taking the same exact sequence as the coding string on again. This this bottom one that's down here is going to be the template strand of DNA. Uh, now you'll notice that there is going to be a region here highlighted by this box which is represented representing an RNA DNA hybrid region. And so you can see that these free our DNA nucleotides that air floating around in the cell are going to be incorporated into this Arna molecule by the RNA polymerase enzyme. And so this here is representing the overall overview of transcription. And again, as we move forward in our course, we're going to break down this process of transcription inm or details looking at it step by step by step. But for now, this year concludes our overview of transcription, and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video