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17. Mutation, Repair, and Recombination

Induced Mutations


Induced Mutations

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Hi in this video, we're gonna be talking about induced mutations. So induced mutations, mutations that are induced is typically a current laboratory setting and we typically call this muda genesis which is some type of creation of mutations in a laboratory or potentially just in the environment. But it's usually caused by some type of chemical or mutation that causes the mutation. So there's a few different ones that I want to mention. The first is based analogs. These are chemicals that resemble bases and so um but aren't basis, so they don't make the right base pairs, they should. So if you put a bass analog into cells or into um you know, an organism then that based analog is going to come in. It's going to fill the place of these bases but it's not going to make the proper pairs that it should. And that obviously when it's not making the proper pairs, when it's taking a place of a base that's gonna cause a mutation, then we have calculating agents, these adam alcohol group and onto the basis. And this also offers alters the base affinities, meaning that those bases are not going to bind to the things that they normally would. And generally this results in transitions we have inter calibrating agents and these are chemicals that wedge between the D. N. A. Basis. And they actually cause helix distortions. Now when the helix is distorted, the Plymouth races and things that bind onto it um usually can't overcome that distortion there. Like it makes it like a hill and they can't cross over the hill. And so this ends up generally blocking DNA replication and repair and this can actually result in pretty severe cell death. So these are these are big agents and then finally we have base damage and these are damage to the bases that prevent base pairings. So UV light for instance um causes die MERS between remedying basis and radiation like gamma rays, x rays etcetera can cause damage by creating things called free radicals which you may have seen on your grape juice or something. But free radicals are essentially these chemicals that are fairly harmful because they go around taking electrons and protons essentially from other chemicals. And so ionizing radiation causes a lot of these chemicals and that can go to the D. N. A. And damage it pretty severely. So here's an example of an inner calculating agent which is here. You can see that it's binding to this D. N. A. Where the sugar backbone is here and these are the bases and its binding here. Now if you're a proliferates and you're trying to replicate or transcribe, you're going this way you're gonna get stuck here. This is kind of a roadblock, You can't keep going and that obviously is going to result in pretty severe mutations and even potentially cell death. So there's a certain tests that scientists use called the AMES test and this test various chemicals for their ability to call cause mutations. Now you may you know, we hear all the time O. B. For, I don't know, sunscreen or whatever these chemicals cause cancer. And so these tests are these sort of claims are based kind of loosely on the AMES test where bacteria are exposed to these chemicals and we see well does it denies them. And so um many different ways to do this, but it is important. It's not just putting these chemicals with bacteria because a lot of times we eat things um that has to be digested and when it's digested, there's a lot of different enzymes that can break those chemicals down into something that wasn't originally harmful when you consumed it, but it's now harmful once it's inside the body. So to test that you can use the same test. But what they do is they actually take rat liver extracts which have a variety of proteins which can break down these chemicals and sort of incubate them. Or let them sit with those chemicals and the rat liver extracts will break those chemicals down into whatever they would break down to inside the body. Then you can take those broken down products, broken down chemicals and expose them to bacteria. And you do the same thing. You look for mutations. Um and there's a lot of different ways that scientists can look for how bacteria mutated. But essentially that's how the AMES test works. So with that plus I move on

Which of the following mutagens wedges between DNA bases to disrupt the helix structure?


Which of the following mutagens alters base affinities by adding an alkyl group?


Which of the following mutations would have the least effect on an individual?