in this video, we're going to begin our introduction to DNA replication. But later in our course and a different video, we're going to go into a lot more details of DNA replication where we'll talk about all of the enzymes and all of the steps involved with DNA replication. But again, that's not what we're going to do in this video. We're not going to go into that much detail and this video we're on Lee going to cover the basics of DNA replication, and we're going to introduce some terms that are going to be helpful for you as you move forward in our course, learning about cell division now recall from our previous lesson videos that before any cell can divide, the DNA must first be replicated. And it's important to be able to recognize different synonyms for DNA replication because your professors in your textbooks will sometimes use different words. Toe represent the same exact thing as DNA replication, and so DNA replication can also be described as DNA synthesis or the DNA being synthesized. Or it can also be defined as DNA duplication or the DNA being duplicated. But really DNA replication, DNA synthesis and DNA duplication are all referring to the same thing. And so DNA replication is referring to the process that produces an exact copy of all of the cells DNA. And so the reason that the cell would want to produce an exact copy of all of its DNA is in preparation for cell division, because again, before any cell can divide, this DNA must be replicated so that the cell has an exact copy of the DNA, and each of the resulting daughter Cells from cell division can each get their own copy of the DNA. Now, DNA replication is going to convert what are known as unrepresented chromosomes that have not yet been replicated into replicated chromosomes that have been replicated after DNA replication. And these replicated chromosomes have to identical Sister Crowe motives. Now the sister part here is just referring to the fact that these promoted are identical toe one another. They're exactly the same, and the term chrome it'd is really just defined as half of a replicated chromosome. And so, within a replicated chromosome, there are two chrome attitudes, and they're going to be identical to one another. And that's why they're referred to a Sister Crowe motives. And so, within a replicated chromosome again, there are two chrome attitudes. And, uh, these two Chromatis, they're going to be joined to one another at a position called the Centrum Ear, which is pretty much like the waste position of a chromosome, and we'll be able to see that down below in our image. Now notice. Over here on the left hand side, we're showing you an image of a single unrepresented chromosome that has not yet been replicated. This is what the chromosome would look like before DNA replication, and it is going to be referred to as a chromosome or specifically, an unrepresented chromosome. Now, technically, this single unrepresented chromosome would only have one chroma tid. But we have chrome. It'd here and quotes here because the textbooks won't refer to it as a single chrome. It'd they'll just refer to it as a single unrepresented chromosome. And so that's why we have this guy here from Austin Powers here with the quotes around the chrome. It'd just reminding you that this is really a single unrepresented chromosome. Uh, it would only have one promoted, if that's the way that the text books would use that terminology. But again, this is what the chromosome looks like Before DNA replication noticed that after DNA replication represented by this arrow right here, that the chromosome looks different and that here what we have is still a single chromosome. But it's no longer an unrepresented chromosome. It's now a single replicated chromosome. And so notice that, uh, it has the single replicated chromosome. No, doesn't just have one chrome, it'd it now has to crow motives. And so that's what we're saying down below here is that now there are two identical chroma tits. This right here is one promoted. And this over here is the second crow matted, and these two chromatic are identical toe one another. And that's why they're referred to as sister Chromatic IDs and notice that the sister chromatic are joined together at this position. That's right here, which is really like the waste position of the chromosome. Um, and it's called the Centrum ear. And so really, you can tell if a chromosome has undergone DNA replication or not, just by looking to see how maney chroma Tibbs it has. If it has to crow motives. Basically, if it looks like this. If it looks like an X, if you will, then you know that it's going to be a replicated chromosome. But if it does not look like an X, then you know that it is an unrepresented chromosome. And so this year concludes our brief introduction to how DNA replication converts unrepresented chromosomes into replicated chromosomes with two identical Sister Crowe motives, 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.