In this video I wanna talk about the polymerase chain reaction or PCR. Remember the key thing with the polymerase chain reaction is that it allows for the amplification of DNA. Why is that so important? If you can't turn a piece of bacteria into over a trillion of them in a thermal cycler then basically they don't have enough to analyze it. Maybe geneticists could work with DNA and that'd be about it. You wouldn't have forensic microbiology and you wouldn't have forensics and DNA you wouldn't have paternity testing you wouldn't have zoologists and archeologists and everyone else working with DNA. So we have to find a way to amplify DNA and this is how you do it. So a polymerase chain reaction used to involve this combination of raw materials plus these water baths but now a thermo cycling machine does it. What you need is that you incubate your DNA at degrees Celsius or Centigrade for one minute. That breaks these hydrogen bonds apart it separates them so your strand of DNA is now separate. Your double strand of DNA is now separate. That's where the ingredients come in to play so what you have in here you have the enzyme DNA polymerase this would come from a thermophylic bacteria like Thermus Equatacus. And the reason for that is because those R enzymes couldn't survive the heat here the degrees and degrees et cetera without being denatured. So that's why you use this thermophylic DNA polymerase. But the DNA polymerase can read one of these strands of DNA and then may create the complimentary strand. Where it reads an A it puts a T. Wherever it reads a C it puts a G et cetera. Alright next we need the building blocks. So we have the DNA we have the enzyme that can read it. We have the nucleotides A's C's G's and T's. I can't build DNA without them. And the last ingredient we need is this little primer here. So the primer's job is gonna be kind of like the bottom of a zipper. The DNA polymerase can't just work out of nowhere. So you need the primer to be the starting point of we're going to make copies of DNA. Actually serves a dual purpose though while it does that it also localizes the replication or amplification of DNA to the piece that you want. You don't want all three million base pairs whatever. But you just amplify the piece that you want by using the appropriate primers. So those are all the players involved. Go ahead and clear this. So degrees the double strands separate you now have two single strand pieces of DNA. At degrees Celsius the primers attach. So you know DNA can only be copied in the five prime directions you see how the primers on the bottom of one and on top of the other? So the primers attach for a couple of reasons. Number one it gives the enzyme DNA polymerase a place to work from. And number two it keeps these double strands from going back together. Because what was just at degrees what's to stop those two strands from going back together? That's why you put a whole bunch of primer in here to make sure it doesn't happen. So degrees Celsius separates these two strands of DNA degrees Celsius for a second minute actually attaches the primers to the single strand and pieces of DNA and then at degrees Celsius for one minute the enzyme DNA polymerase will actually copy the target DNA so after three cycles or three minutes of this one cycle we've now turned the one piece of DNA into two. Then they goes back over two becomes four. Four becomes eight. Eight becomes . becomes . You get the point so. That's how the polymerase chain reactions and then how it works is or it's function is to amplify DNA that allows you to look for infectious diseases in places where you couldn't normally see them. That will be the only way to do it. to look for things like drug resistant strains of bacteria you can use the PCR. Especially for things like the micro bacteria because they take up to six weeks to grow. So you could actually genetically look for them instead of trying to grow them on a Petri dish. Those would be a few examples and the fact they just all fields of science now have genetics or DNA to work with. Alright that's the polymerase chain reaction.