in this video, we're going to begin our lesson on methods of inducing mutations. And so recall from our previous lesson videos that induced mutations are controlled deliberate mutations that occur due to an external source. Now in order to increase the mutation rate in bacteria that are being studied, scientists will typically use muted agents to increase the mutation rate. And so muted agents are defined as any chemical or physical agent that can cause mutations. And carcinogens are really just specific types of munitions that will contribute to the development of cancer. And cancer is characterized by uncontrollable cell growth. And so if we take a look at our image down below, notice that the top half of the image is focusing on the term mutation, whereas the bottom half of the image down below is focusing on the term carcinogen. And so what you'll notice is in the top half of the image with the mutation, the mutation is going to be any chemical or physical agent that is used to increase mutation rates or to cause mutations. And so notice that a mutagenic chemicals being added here to this bacteria and the mutation is going to lead to mutations. Now, mutations do not necessarily lead to cancer and so notice that this mutation does not lead to cancer. And so it does lead to a mutation, a change in the DNA sequence, but it does not necessarily lead to cancer mutations don't necessarily lead to cancer. And so we have a mutation here without cancer. Now notice that the carcinogen is a specific type of mutation that leads to the development of cancer. And so the carcinogen here is being added to the bacterial cell and notice that it does lead to a mutation. But this mutation leads to the development of cancer. And so notice that we have uncontrolled division of these mutated cells over here. And this is due to the carcinogen. And so really mutations will lead to um mutations but not necessarily cancer. And carcinogens lead to mutations that lead to the development of cancer. Now, over here on the right, what we're showing you is the OSHA symbol and OSHA stands for occupational safety Health Administration. Uh this is the OSHA hazard symbol for carcinogens and munitions. And so if you see this symbol on any kind of chemical or physical agent, then you should be careful because that substance is going to be either a carcinogen or mutation. Uh and so this year concludes our brief introduction to methods of inducing mutations. Uh and we'll be able to talk more about other methods of inducing mutations as we move forward in our course. So, I'll see you all in our next video

in this video, we're going to talk a little bit more about chemical munitions or chemicals that can cause mutations in the DNA. Now, some chemical munitions can cause chemical modification. And this is referring to chemicals that have the ability to modify or alter the structure of the nitrogenous bases in the D. N. A. And an example of a chemical munition that can chemically modify the nitrogenous bases are calculating agents. And these chemicals that can chemically modify can also alter the base pairing abilities of the nucleotides that were modified. And so if we take a look at our image down below at this chemical modification box here in purple notice on the left hand side over here, we're showing you a guangying nitrogenous base and this guanine nitrogenous base. It normally forms three hydrogen bonds represented by these three dotted lines that you see here. And usually the guanine are going to base pair with sido scenes or sees. And so you can put a C here uh for the guanine base pairs with seducing uh And again, this is under normal conditions. However, if a chemical mutation that's capable of chemical modification is added such as an alka waiting agent, then it can chemically modify an existing nitrogenous base and it can change its properties. And so notice in this case that a methyl group is being added here at this position where the carbonnel group used to be. And so now there is one less hydrogen bond that can form here. And so there's only two hydrogen bonds that form. And so because this is a chemically modified base where it's modified with a methyl group. We actually call this method all Guan E. And so metal guanine, which is this base that you see here, it has different base pairing abilities. And so instead of base pairing with side of sean's, it can base pair with thigh means and that is not supposed to happen. Guanine are supposed to base pair with C's citizens. Uh not with teased, I means. And so this chemical modification can lead to mutations in the DNA and cause issues. Now, next, what we're going to talk about our base analog and base analog are actual chemicals that are just structurally similar to uh nitrogenous bases. However, these base analog there, although they are very similar to the nitrogenous bases, they are not exactly identical. And so they do have different base pairing properties. Now the base analog are not necessarily going to be chemically modified, like what we've seen up above. Instead, these base analog scan sometimes exist in nature. And so these base analog scan sometimes mistakenly be incorporated um instead of incorporating the normal base. And so if we take a look at our image down below, notice on the left hand side over here, we're showing you a normal base and on the right hand side over here we're showing you a base analog. And so this one could exist naturally in nature like I mentioned. And so uh notice that it is different only different from the normal base at this position here, the normal base has a methyl group. Whereas the base analog here has a Boromir in group and so occasionally sometimes base analog Czar mistakenly incorporated uh instead of incorporating the normal base. And so when based analog Czar mistakenly incorporated they can have different hydrogen bonding abilities and different base pairing abilities. And so this can once again lead to mutations in the DNA. And then the last chemical munition that we're going to talk about our inter collating agents. And these are really flat molecules that have the ability to insert Between two base pairs and therefore increase the chance of a point mutation occurring. And so if we take a look at our image down below at the inter collating agents over here, notice on the left we're showing you A D. N. A. Molecule and here we're showing you the addition of an inter collating agent, pro flavin. And so this inter collating agent is a flat molecule that has the ability to insert itself into uh in between two bass players. And the insertion of this inter collating agent can change the structure of the D. N. A. And increase the chance of a point mutation occurring. And so this is another example of a chemical mute agent. And so this year concludes our brief lesson on chemical munitions and we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.

in this video, we're going to begin our lesson on radiation mute agents. And so the exposure to certain types of radiation can actually cause mutations to occur in the D. N. A. And really there are two types of radiation that are commonly used as mutations. The first is going to be UV light or ultraviolet light and the second is going to be x rays. Now U. V light or ultraviolet light causes formation of nuclear based dye MERS that distort the DNA structure. More specifically, it causes the formation of what are known as thinning die MERS and timing die MERS occur when covalin bonds formed between adjacent timing bases in the DNA. And so these timing diners actually cause issues because DNA replication and transcription can actually not continue past the distortion caused by these timing diners. And so the cell typically ends up dying when these timing diners are present. And so if we take a look at our image down below notice that we're showing you UV light used as a method of uh of being a mute agent and so notice that we have the D. N. A. Is over here. And what you can see is that ultraviolet light which can be present in the sun. Um can cause these timing die MERS to form. And the timing diamonds, you can see that two adjacent to, I mean Zarco violently linked and bound together and it distorts the structure of the D. N. A. And so once again it can cause uh this is somewhat of a mutation in the D. N. A. Change in the D. N. A. And these timing diners can cause cell death because it disrupts processes such as DNA replication and transcription. Now x rays are going to cause single and double stranded breaks in the D. N. A. And so rather than causing thiamine diners, what you can see with these X rays over here is that the x rays will cause the D. N. A strands to break. Sometimes it's a single stranded break. Other times it's a double stranded break. But these single stranded DNA bricks is being shown here when they are repaired A lot of times, it will introduce mutations. And so this is why X rays can be used as mutations and specific scenarios. And so this year concludes our brief lesson on radiation mute agent and we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.