So now that we've briefly introduced preliminaries chain Reaction or PCR in our previous lesson video, it's fair to ask, Why do we use PCR? Well, it turns out that scientists will use PCR for many, many different reasons. And that's because PCR is a quick and efficient process for generating many identical copies of DNA in a test tube. Now, DNA cloning, which occurs inside of living cells and does not occur in test tubes, is going to be more accurate. But it's actually a less efficient process. And that's because, recalled DNA cloning occurs inside of cells. And although there are less mutations inside of cells, it's going to take a lot longer to amplify the D N a inside of cells. And that's because a lot of time cells take 24 hours or more to be able to grow. And then after you grow the cells, you have to isolate the D N A. And that's a whole another step within itself. And so PCR is much more quick and much more efficient. And so, in our example down below, we're going to take a look at, just in general, how PCR or what PCR can do. And so, uh, it says here that PCR can be used to amplify the amount of D N A taken from a crime scene so that a detective can actually investigate the d n A. And so down below, over here, Notice we have this scientist that has a test tube here with some DNA that perhaps was found at a crime scene. But notice that there's not a whole lot of d N A within this sample. And so notice the scientist is saying, I wish I had more of this particular DNA of interest so that he has enough DNA to be able to run tests on it. And so this is where PCR can come into play because the process of PCR polymerase chain reaction can amplify the amount of DNA to make many, many identical copies of the D N A. As we see over here. And so the scientists saying, Wow, that amplified very, very quickly. And the process of PCR can be done in a relatively short period of time, maybe something like two hours 1.5 2 hours, whereas DNA cloning again is going to take much, much longer, which it could take well over 24 hours in many cases. And so why do we use PCR to make many identical copies of D. N A N a test to very, very quickly and efficiently? And so again, as we move forward in our course, we're going to continue to talk more and more about PCR and the steps of PCR, so I'll see you all in our next video.