Types of Mutations

Hi in this video we're gonna be talking about types of mutations. So I really wish that this would be super fun to go over. But it's really not. It's just a ton of vocab of different types of mutations and how they affect different things. And so I've tried to organize it so that it's like in some kind of order but generally it's just gonna be this video and then the one that follows is going to be just a bunch of vocab words that you need to memorize. The good point is that most of them are common sense. They make sense of why they're named that way. So hopefully won't be too hard to remember them. So this is about mutations and there are many different types of mutations. So one way to describe them is how they arise. So the two ways that they can arises spontaneously, meaning they just occur just sort of randomly or induced, meaning that something has caused them. So spontaneous mutations are those random occurrences. Things like, you know, DNA replication just randomly has errors occasionally. That's the type spontaneous mutation. And induced mutation is something that's caused. Um And these can occur via natural ways or artificial agents. And so these can occur by scientists in the laboratory sort of inducing mutations. They can also come from different types of UV radiation, for instance, from the sun. Those are induced mutations because they're caused from from something that isn't just a random occurrence. Now, a second way to classify mutations is where the mutation occurs. And so we have somatic cells mutations which are of course occurring in somatic cells and germ cell mutations that occur in germ cells and this is a really important part because somatic cell mutations only affect the organism itself, it doesn't affect the offspring at all. But if the mutation occur in the germ cell, so the sperm and the egg, that means that's going to be passed on from generation to generation to generation. So obviously these germ cell mutations have a lot more ability to severely affect multiple generations where somatic cell mutations generally only affect the individual that has that mutation. So here's just a picture. If you have a somatic cell, you have a mutation here in red, that's not going to be passed off. Whereas a germ cell you have the same mutation, it will be passed on to offspring. Now the first type of mutation I really want to talk about is a point mutation and this is a mutation that occurs in one single nucleotide. There are many different types of point mutations and this is where it starts getting vocab heavy, where it's not necessarily, you know, intuitive right, somatic and germ cell mutations that makes sense. But some of these terms you may have never heard before. So the first type, the first class of point mutation is a base substitution, meaning that you're substituting one base for another. So you're changing one base into another and there's two types you have transitions, this replaces the base with one from a similar category. So this will be appearing appearing or it could be perimeter into promoting and then you have trans versions which is the opposite. So you do pure into primitive eating or primitive appearing, right? So those are the two differences. But essentially you get one base, you have one base that's supposed to be the right base, It's mutated and that changes it for another base. Then you have base insertions which is the second class and base deletions which is the third class. And they do exactly what they say. But they sound like they'll do insertions, adds nucleotides and deletions removes them. Um you can have mutations called an in del mutation where an insertion and deletion occur at the same time. Now if there's one insertion of one nucleotide and a deletion of one nucleotide that's not going to change the length of the sequence for the gene. But there can be an assertion of three nucleotides in a deletion of 18 and then that changes the length of the gene that's being mutated and based insertion and deletions easily affect Cardin's. I remember code in there, those three nucleotide sequences. So if you delete this one then you have now made this the second position in this one the fourth and that drastically can affect Godin's and how they're red. So here we have an example if you switch a appearing two appearing that's called a transition. But if you mutate a peering or so on A to a C which is promoting that's called the trans version. So you can see that different ways that this happens causes different things where trans versions are in red and transitions are in blue. So a third way to classify mutations is their effect on code ins which is what I said before. And I remember a quote un's those three nucleotides code Now if a mutation can be called silent or synonymous depending on the book that you use if that mutation changes a code onto another coat on. But that code on codes for the same amino acid. So remember there's a bunch of different code and that code for the same amino acid. So if you just switch out the nuclear tides but those nucleotides still code for the same amino acid, it's not going to affect the protein because the same amino acid is produced. So we call that a silent mutation because it is a mutation at nucleotide has been changed but has no effect on the protein and therefore it's silent. We have mis sense mutations and this is a change in a code on that changes that code on to one that codes for a different amino acid. So MS sense was the same amino acid miss sense is going to be for a different amino acid and there's two types of this. These there's conservative and non conservative, conservative changes the code onto another coat on with a similar chemical nature. So if you have if it originally coded for a hydrophobic code on or hydrophobic amino acid and a mis sense mutations would be if it changed the amino acid but it did it to another hydrophobic. So you can you remain the you keep the chemical property even though the amino acid is different. Non conservative is more severe because the code on is changing to another code on but it's of a different um chemically different amino acid. So if you change if you have to change a code on right, if it is a mis sense mutations and the code on is actually changing to a different code on and that's coding for a different amino acid. Would you want one that's more similar to one that's more different. Right? If you're a gene producing a protein you want one more similar because you want to retain as much as possible with this mutation, the chemical nature that it's supposed to be so conservative. Mis sense mutations are generally less severe than non conservative ones. Now the third type is a nonsense mutation, this changes a code onto a stock code on. Obviously that's it. You know, if a stop code on appears right in the middle of the gene then that's going to only produce the first half of that protein. It's not going to be functional. It's probably gonna get degraded and um that's not gonna be good. You're not gonna want that. It's not it's really going to harm the phenotype of the organism. And then finally we have frame shift mutations. And this is where the code in alters the reading frame. So if the reading frame is this 123123 a frame shift mutation would mark out somehow delete two. Right so now your codenames are 131231 23. And then something here right back up. So you can see that now this 123123123 is gonna code for something completely different than 13123123. Right? So frame shift mutations alter the code on reading frame and that alters the amino acids that are produced um forming the protein. So here we have this um some different examples of point mutations. Here's the silent one where you can see that the normal is going to be T. T. A. And now it's switched or T. T. T. And now it's switched it to A. A. And it doesn't really matter because both of these encode for listen. So listen will still be produced if the normal is T. T. C. And then it switched it to T. T. T. This is the RNA. Here. Now the nonsense mutation takes this normal T. T. C. And changes it to A. T. C. This encodes for a U. A. G. Which is a stock code on it's going to mess up the protein. Um very badly then you have MS sense. With conservative and non conservative. So a conservative is it changes the code on, it changes the amino acid so it went from listening to argentine. But this arginine has a similar chemical structure. So you can see that's kind of represented by this purple color here whereas the non conservative changes the amino acid but it does so in a completely different way. Whereas these are basic. I know that because here and this is polar and these are completely different chemical structures which will affect the earliest for the polar will affect the proteins composition and structure. So that is kind of I said like I said, there's going to be a lot of vocab. It's gonna be a lot of vocab in the next video too. But this is kind of the first set of understanding the different types of mutations. So with that let's now turn the page.

Okay so now we're gonna talk about based distortions and based distortions are a type of mutation that affects the overall two l. Structure of the basis. And usually this has some kind of major impact on the structure of the helix as well. And so the two most common ones are when actually the bases lose a part of their structure. And so we give these two different names depending on the type of base that's lost. Luckily it's very easily to figure out. A periodic site is going to be a base that has a region that's lost appearing right? A pure in eclac appearing. And that process is called deep urination is the losing of that hearing. Then these are more common. But then we have the a prayer um identix sites and these are ones that have lost their perimeter things. These are very easy terms to remember. Now there is a second type that isn't losing part of its structure but is not part of its base but a different group, a different chemical group. And so d emanation is the removal of the amino group from the base or molecule in the D. N. A. And so this process can actually um change the type of base that's there. So for instance a side of scene if you remove the amino group turns into a euros L. And that's obviously a very different base and can definitely introduce mutations that's supposed to be a sight unseen that pairs with guanine. But if you have a euros L. There that does not pair with guanine. And so that creates all sorts of mutations. This also if you remove an amino group from attaining changes it to this weird base you've probably never heard of here. But essentially this is in our normal base right? Like this is not gonna para normally and that induces different types of mutations. And then based damage can also occur from oxidative damage and you may be like I don't know what oxidative damage is but essentially oxidative damages when you have these reactive oxygen species is what they're called. They're called R. O. S. But essentially what that is is it's going to be an oxygen molecule that's very reactive and very harmful and very toxic. And that causes um it can affect the bases. It can affect the D. N. A. Can affect the helix because it goes in and it reacts with those bases because it's very reactive as this oxygen that's very reactive and it can cause significant harm to the base. So an example of some reactive oxygen species is this molecule here which is oxygen but it is missing um the 02 negative notice here that's not good. We have hydra peroxide which we know is very harsh chemical and then even some types of hydroxy ALS can come in if they're not properly contained and really affect the distortion of the base and they can chemically alter the bases. And we saw here that if the base is chemically altered that can actually change it into another base or something entirely different that won't react properly or bind properly with the other complementary base. So based distortions are a huge form of DNA damage. So here's an example of delamination of cytosine to uracil. So here's sight unseen over here and here's your sl and you can see they look very similar, but you add some water, some other chemicals. And this obviously changes in a few different ways to your cell. And that is not good because if it's supposed to be side of things, you don't want to hear a cell in their causes mutation. So with that let's not move on.

Okay, so now we're gonna go through and talk about mutations and the different types of phenotype that cause and what all the terminology is used to discuss mutations of phenotype. So the fourth way to classify mutations is their effect on approaching activity and how that affects the phenotype of the organism. So there's two classes of mutations, loss of function and gain a function. And if we just if you were to take a guess what that meant, you would probably get it, loss of function means that the protein's activity is losing its normal function whereas gain a function, meaning that it's it's more efficient, it has higher activity. It's it's gained functional ability the protein has. And so um There's one type of loss of function called a null mutation and that means that there's a complete loss of function. This protein is not at all active. So loss of function can just mean it has a weaker activity. But a null mutation is going to be, it's completely out of the game. It's not doing anything 0% function. So that's the first way you have visible mutations. Obviously these are going to be mutations that you can see physically. So these are affecting the phenotype of the organism, couple different classes. You have nutritional ones which can cause a loss of ability to synthesize some type of amino acid or vitamin. So we all need different amino acids and vitamins to live in our body synthesizes some of them or we consume them in our bar body, breaks them down into what we need. If there's mutations in any of those processes and synthesizing what we need or breaking down what we need, then that results in a nutritional mutation. Now you can't just look at someone and see that, but they do. Typically the people with nutritional mutations do typically have very severe phenotype and if they're not getting that nutrient, that's a nutrient deficiency and that results in some kind of phenotype, you can visibly see the second type is behavioral mutations. These are really hard to study in a lab because its behavior and behavior is very different for individuals. But there are some mutations that can affect changes in behavior of an organism. And obviously you're going to see that because its behavior and they're acting a certain weird way. Now there's a certain class called conditional mutants and these are only detectable under certain conditions, meaning that they are active. So they can cause harm under certain conditions only and under normal conditions, they don't cause harm. So, the best example of this that your book uses is temperature sensitive mutants. And these have been designed by scientists and to study in various organisms, fruit flies, worms, etcetera, mice, even, and essentially at some higher temperature generally, how these work is that at normal temperatures, these are expressing wild type levels of gene and protein, right? Those are being expressed. And you have all type levels at some higher temperature or some lower temperature those temperatures, then mess up the protein and therefore you can see the mutants phenotype because now that protein is not being produced correctly, it's being produced in this mutant temperature sensitive way that is causing some kind of genotype on the organism. So conditional mutants are a lot of times used by scientists to study various types of mutants which wouldn't be able to be studied otherwise. Um then we have lethal mutations, caesar mutations that cause death of the organism. So lethal mutations are often studied by scientists and conditional, right? Because if you are trying to study a lethal mutation, if you put that into an organism, that organism is going to die and it's never going to develop, right, it's never going to mix an egg and sperm together, it's going to die as a fetus. But if you make it a conditional mutant, then you can grow it. That protein will be expressed normally. That organism will develop in utero after it's born. You can then move it to a different temperature and study the effect of the genotype under a condition where the organism is still alive. So, but lethal mutations cause death if they are present. And then finally, the least exciting is the neutral mutations which are mutations that have no observable effect on the organism. Now, if you had to guess some of the mutations that we've talked about before, especially the ones that may be affected cardin's, which type would you say is most likely a neutral mutation. Right? That would be a silent mutation, right? Something that changes one coat on to another coat on. But that coat on still codes for the same amino acid Most of the time, neutral mutations are not affecting code ins at all. Sometimes they do. And they're found in places like introns for instance, that aren't coded anyways and they have no effect. Um And so neutral mutations have no effect on the organism, whether because they're encoding regions but code for the same amino acid or because they are non coding regions and therefore it doesn't really matter for the organism whether or not it gets mutated. So here we have an image that is looking at the difference between loss of function and gain a function, you scroll up so you can see so here we have wild type and you can see there's two alleles, right? For each, each gene there's two alleles. So both the wild types are producing the same number of these like little circular proteins. If you have a loss of function you get one allele that produces the same and then the mutant leo you get a decreased amount of black circles for the gain of function you have water leal it's wild type and mutant you can have a bunch of gain of function which will create a lot more little black circles. Um Now if you had a null mutation there would be no black circles. And if you had a mutation in both alleles that would obviously be more severe because both of those would be producing these altered amounts of little black circles and not just one that has a mutation. Now there's a 5th way to classify mutations based on their effect on individual alleles. So again, lots of vocab, sorry for this, but we just got to get through all the vocab and then we can get some more interesting stuff. So we have hyper more fick mutations and hyper morphing mutation is a loss of function mutation and this still produces some type of functional protein. So this would be here. This would be called a hyper hypo more fick. The reason is because they're still approaching present, but it's probably weaker than the normal amount of protein that's present. Half low insufficiency, which we you may have heard before probably a while ago now. But happily insufficiency describes when there's a wild type lille still left. So only one of the cells are mutated. But the one wild type of deal is not enough can't provide enough gene product. So the organism still appears mutated. So the other is usually a null or generally loss of function. And when it is, it's you only get half the gene product and that's not enough to create a normal phenotype of the organism. We have a dominant negative dominant negative is when you have a mutant elio and a wild type of will and the mutant allele, whatever is produced from it produces some kind of protein that blocks the production of the other. And so dominant negatives are used a lot by scientists to study various genetic things. But essentially you have a wild type of mutant. That mutant creates something that sort of shuts down that wild type from functioning. So again, that organism, even though it has a wild type of deal looks very much mutant. Now we have hyper more fick, this is kind of the opposite to hypo that we talked about above. Hyper more fick gain a function that produces a more efficient protein than wild type. So that would be this situation here and then we have nia more fick mutations which is generally a mutation that produces some kind of novel phenotype. So it's not I mean it's a mutant phenotype but it's not necessarily worse off. It could be potentially better for the organism, but it's generally a different phenotype than we've ever seen before with this gene in the cereal. So here we have um wild type alleles, right? They have 100% activity if there is some type of mutant here, it's a no alil if there's zero activity from this wanna leal it's high polymorphic if there's 30% activity and then it's hyper more Fick if there's 100 and 60% activity. Right? So these are kind of the differences between how they're affecting alleles and the phenotype. And then finally the little last class of vocab I know you probably have like a whole sheet written down at vocab words. But this is the last one. It's the sixth way and it's by their suppression activity. So there are mutants called suppressor mutants. And these mutants are these mutations cause this depression of another mutation. So there's two mutation and one of them causes the suppression or the block of another. So suppressor there's two types introgen. IQ notice here is the T. R. A. That separates this from the next one. Entra genic. Their mutation sounded the same gene as the mutation being suppressed. So if we have a intra all right try then you have a mutation here and a mutation here and this one is blocking that mutation and it's in the same gene then you have inter genic. This is gonna be better. And this blocks or as a mutation and a separate gene than the mutation being expressed. So it can even be on a different chromosome. So we'll do this. So we have a mutation here and a mutation here and this one comes out from even a different chromosome and causes suppression of this. 2nd mutation blocks it. So suppressor mutations exists. They're important. Sorry for all the vocab. I really truly am. I wish it were easier. But hopefully the majority of them kind of make sense into why they're called that way. Um But if not just keep reviewing and making sure that you know what the differences are between these vocab words, because if you don't, then it's going to make answering some of the word problems that I'm sure you'll get much more difficult. Um So with that let's now move on.