Introduction to Transcription

by Jason Amores Sumpter
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in this video, we're going to begin our introduction to transcription and so recall from our previous lesson video. That transcription is the process that builds Arna by using the DNA within a gene as the coding template. And so this is the process of building our and a now also recall from our previous lesson videos that genes are really referring to small units of DNA that encode a product. For example, a protein and so genes in order to create a protein will need to be both transcribed and translated. And so here we're talking about the first step of the process, which is transcription being transcribed now, in order to better understand transcription. It's helpful to, uh, describe some specific sequences of DNA that mark where transcription of a gene begins and ends. And so the first ah sequence of DNA that you should note is called the promoter. And so the promoter is a small stretch of DNA sequences where transcription begins, and so the promoter is really just the site where the RNA prelim a race is going to attach, and the RNA preliminaries, um, is going to be the primary enzyme involved in transcription And so the RNA polymerase, as were mentioning down below here, is going to be an enzyme, the primary enzyme that is going to prelim arise or build Arna from scratch and turns out that RNA prelim erases do not need a primer like DNA Polymerase is due on DSO. Arna proliferates does not require primer. And again, we're going to talk a lot. Maura about RNA, polymerase and transcription as we move forward in our course here. But it's important to note that the promoter is going to be the sequence where transcription begins, because this is the site where the RNA polymerase first attach is now. The Terminator, on the other hand, is also going to be a stretch of DNA sequences. But this is where transcription is going to end. And so if we take a look at our image down below, which you'll notice is on the far left, we have a chromosome, a replicated chromosome, which we know consists of DNA and protein. But if you unravel this chromosome, which you'll find is there is DNA in here and some of these DNA, some of this DNA are going to be jeans. They encode a product like a protein. And so if we take a look at a typical gene on zoom into it, which will find is that it's going to have a green region here that we're going to be referring to? Is the promoter and the promoters again? The small stretch of DNA sequences that allows for the are Nepal Emery's to bind, and this pink structure that you see here is the RNA polymerase. This is the primary enzyme involved with transcription, and so the RNA polymerase. What it does is it will bind to the gene specifically at this promoter region. And then the RNA preliminaries will transcribe the coding sequence of this gene and then the Terminator over here at the end. It is, of course, where transcription is going to end, and collectively, the promoter, the coding sequence and the Terminator. Basically, this entire region right here is referred to as the gene. Now, sometimes there are other important sequences that surround a gene, and so it's important to be able to refer to the directionality of those sequences that might be outside of the gene. And what they use are the terms upstream of the gene and downstream of the gene now turns out that downstream of the gene is referring to DNA sequences in the same direction in the same direction as transcription. And so you can see the arrow down here. You can think of little fishies downstream, and the downstream is going to represent, uh, DNA sequences outside of the gene that air in the same direction of transcription. And in this case, because the RNA polymerase binds here, it's going to be transcribing in this direction, and so downstream is in the same direction of transcription. Now the opposite direction is going to be referred to as upstream, and so upstream is going to refer to DNA sequences and the opposite direction of transcription. And so again, the RNA polymerase is binding at the promoter and transcribes in this direction. But upstream of the gene is going to be in the opposite direction of the transcription direction. And so this year concludes our brief introduction to transcription, and as we move forward in our course, we're going to continue to learn Mawr and Maura about transcription, so I'll see you all in our next video