- No let's talk about restriction enzymes. We wouldn't be able to recombine DNA without them. But we don't make them. We're just lucky enough to find them. So they were first discovered or at least isolated in . So their job basically they're probably a big part of a bacteria's quote unquote immune system. So if a phage infects a virus as we learn with with process of transduction it can destroy all the bacterial DNA. And basically turn that bacteria into a factory producing more viruses. So bacteria respond by using restriction enzymes. Their job is to cut up or hydrolyze bacterial phage DNA. So to protect the bacterial DNA from being destroyed by this virus how we use it is that it's because it's specific. So as you see here EcoR Escherichia coli only is gonna cut between the G and the A. On the sequence G-A-A-T-T-C so they're very specific and that means that we can so you know they're always gonna cut that restriction enzyme. Always gonna cut that sequence gonna cut the same way every time. So you see some are shorter. Only four. Some are gonna be six. Some are gonna be eight. But the more base pairs base sequences you have the more specific it's gonna be because this is gonna cut anywhere in the genome where it finds G-A-A-T-T-C. There hundreds of different types of restriction enzymes. Here's only four of them. But then as you can see by the name they're named by where they were found. So they have these sticky ends. That what happens is anytime you use the same restriction enzyme you can cut out a piece of DNA and then use these sticky ends and the same restriction enzyme to put in another piece of DNA. So basically you can take out a chunk of DNA and replace it with a different piece. So that's how restrict the basics of how restriction enzymes are going to work. That's what they're selling not much to see there but that's what restriction enzyme is. They're not made they were found. They're traditionally part of bacteria's quote unquote immune system. And then we use them because if you can cut out piece of DNA that means you can replace it with a piece of DNA the same size and shape. Which means you can cut out a bad gene replace it with a better one. We can do that with single-celled organisms but we need to learn how to do that with humans. With fully functional humans adults.