In this video, we're going to introduce the origin of DNA replication or just the origin of replication. And so DNA replication actually begins at a specific set of DNA sequences that are collectively referred to as the Origin of Replication, or just the ori for short. And so it turns out that prokaryotic cells have a small circular chromosome, and these small circular chromosomes of prokaryotic organisms have just one single origin of replication on their chromosome. Whereas eukaryotic organisms have larger linear chromosomes, and these larger linear chromosomes of eukaryotes actually have multiple origins of replication. In some cases, they can have up to 100 origins of replication or more. And so if we take a look at our image down below, notice on the left-hand side over here, what we're showing you is prokaryotic DNA replication, and on the right-hand side over here, what we're showing you is eukaryotic DNA replication. And what you'll notice is that the chromosome of prokaryotes is circular, and the circular chromosome of prokaryotes only has just one single origin of replication. One origin of replication. Now if we take a look over here at the eukaryotic chromosome, notice that its chromosome is linear, and the linear chromosome actually has 2 origins of replication in this image, but again they can have many origins of replication, so multiple origins of replication. And so what you'll see here is that the darker blue molecules represent the old original parental DNA strands, and, as DNA replication proceeds, it's going to occur and begin at this origin of replication. And so what you'll notice here in this image is that the new DNA strands are, in the light blue color, and of course, these little pink structures are representing RNA primers, which we're going to talk more about the functions of these RNA primers, as we move forward in our course. But the point here is that the origin of replication is where DNA replication is going to begin the process. And so, you can see over here, DNA replication is going to begin and proceed. And so, this here concludes our brief introduction to the origin of replication, this set of DNA sequences that marks the beginning of DNA replication. And we'll be able to talk more and more about DNA replication as we move forward in our course. So I'll see you all in our next video.