Mendel's Laws

in this video, we're going to begin our introduction to Gregor Mendel's laws. And so, through his research with P plants, Gregor Mendel was able to propose to fundamental laws of genetics. And so the first fundamental law of genetics that Gregor Mendel proposed is the law of segregation. And the second fundamental law that Gregor Mental was able to propose is the law of independent assortment now moving forward. In our course, we're going to talk about each of these laws of genetics in their own separate video, starting with law of segregation and then moving on to the law of independent assortment. However, it turns out that we've actually already covered both of these laws and our previous lesson videos when we talked about my oh sis and so really moving forward as we talk about both of these laws, what you should find is that it's Mawr review than new information. And so that being said in our next lesson video, we'll talk about the law of segregation, so I'll see you all there

in this video, we're going to introduce Gregor Mendel's law of segregation. And so the law of segregation basically says that during gammy formation or during my oh, sis to a Leo's of the same gene are going to segregate or separate from each other and end up in different gimmicks Now, in other words, the law of segregation basically says that gametes are hap Lloyd and that they will Onley receive one copy of a gene or a Leo. And so, if we take a look at our example of law segregation down below, uh, notice that at the top what we have is a homo zegas dominant cell that has, uh, two dominant Jalil's. We have a hetero zegas, uh, cell that has one dominant Leo and one recess of Leo. And then we have a Hamas, I guess, recessive cell that has to lower case Ah, Leo's to recessive alleles. And so notice that before my oh sis can take place, the DNA needs to be replicated. And so when the DNA is replicated, we get duplicated or replicated chromosomes, and that means that we have an extra copy of each of these a Leal's and so notice that we have a total of four folios at this temporary period just before my oasis begins. And after my oasis, one of my houses to each of these four Leos are going to segregate and separate independently. And they're going to, uh, end up in gammy so that each gammy on Lee gets one copy of the polio for that particular gene, and the same applies for the hetero sites, uh, cell. It's going to undergo DNA replication to make an extra copy of each of the wheels that it had. But ultimately they are all going to segregate or separate from one another by the law of segregation, so that each of the game it's on, Lee gets one copy of the Ah Leal's and finally, last but not least the same applies for homos, I guess. Process it again just before my Asus begins. DNA replication occurs where the chromosomes are going to replicate or duplicate, and there will be an extra copy of each alil. But through the law of segregation, all of these illegals once again are going to separate and segregate from one another so that each of the game it's on. Lee gets one copy of the illegal, and that makes all of these game meats hap Lloyd. And so, once again, the law of segregation is something that we've already discussed when we talked about my oh sis in our previous lesson videos. But Gregor Mendel, just through the study of his pea plants, was able to come up with this law of segregation. And so this here concludes our introduction to the law of segregation, and we'll be able to get some practice applying these concepts as we move forward in our course. And then we'll talk about the law of independent assortment, so I'll see you all in our next video.

So now that we've covered the law of segregation in our last lesson video in this video, we're going to talk about Gregor Mendel's second Law, which is the law of Independent Assortment. Now recall that way back in our previous lesson videos when we talked about my Oh sis, that we introduced independent assortment and so recall from those older lesson videos. That independent assortment is when homologous chromosomes independently and randomly align themselves on the meta phase one plate during my oh sis one. And this is going to create, ah, large amount of genetic diversity in the gametes and in individual organisms. And so Gregor Mendel's Law of Independent Assortment basically says that ah, liel segregation of one gene does not affect the legal segregation of another gene. And this is because these genes are found on different pairs of homologous chromosomes, and the law of Independent Assortment basically says it allows for game. It's with all possible combinations of a Leo's from different genes, and we'll be able to see that down below once we get to our image. Now, Gregor Mendel was able to come up with this law of independent assortment by monitoring the inheritance of multiple genes at once to make this discovery using what are known as die hybrid crosses. And we'll get to talk a lot more about die hybrid crosses later in our course. But for now, you should just know that die hybrid crosses allowed Gregor Mendel to determine this law of independent assortment. And so, if we take a look at our example image down below. What we're showing you is independent assortment that occurs during meta Phase one of my oh sis One and again independent assortment occurs during meta phase one of my Oasis One. So notice that over here on the left hand side, over here on the right hand side, we're showing you two possibilities of meta phase one during my oasis one. And so here, this is representing my Asus. One more specifically, meta phase one of my Asus one And of course, during metaphor is one of my oasis one homologous chromosomes are going to align themselves on the meta phase one plate and there are different possible alignments for these homologous chromosomes. And that's why we have possibility one and possibility to showing you here. Possibility number one is showing you the red chromosomes lined up on the left hand side and the blue chromosomes line lined up on the right hand side. Whereas possibility number two over here is showing you one of the blue chromosomes on the left, the other blue chromosome on the right, one of the red chromosomes on the left and one of the red chromosomes on the right. And so these are different possibilities for the alignment of these homologous chromosomes. And because each of these possibilities is equally likely during my Asus one, Uh, that is what the law of independent assortment is all about, and what you'll notice here is that we've got two pairs of homologous chromosomes. We've got the larger pair of homologous chromosomes at the top, and we've got a smaller set. Ah, smaller pair of homologous chromosomes at the bottom. Notice that the larger pair of homologous chromosomes contains the color gene, and the color gene has different. A Leal's has different versions of the gene has the capital y version of the color gene, which says yellow color, and then it has the lower case. Why version of the color gene, which says green color make green peas and then what we have is the smaller pair of homologous chromosomes contains a different gene. The shape gene and the shape gene also has different Leal's. It has the capital are alil, which is for a rounded shape of the P. And then it has a lower case R version of the gene, a lower case of legal version of the gene, which basically says, make a wrinkled pea a wrinkled shaped peak. And so what you'll notice is that the yellow bands over here on this represent the yellow A Leo and the green bands represent the lower case. Why green polio and the blue bands here represent the capital are round alil, and the orange bands here represent the lower case are wrinkled Khalil. And so again, you can see how the alignment of these ah Leal's on the alignment of these chromosomes is going to lead to different possible, uh, different possibilities in the gangs. And because all of these, because of the law of independent Assortment and the segregation of one gene, does not affect the segregation of the other gene, it allows for Gambians with all combinations of illegals from different genes, which means that we can have a yellow round P or a yellow wrinkled pea. Or we could have a green round P or a green wrinkled pea because of independent assortment. And so you can see that we have our yellow round peas over here represented here. Our green wrinkled peas represented here, our green round peas represented here and our yellow wrinkled peas represented here. And so again, it's because of independent assortment creating these different possibilities that allows for all of these different combinations that we see down below. And this, once again, is referring to the law independent assortment. How these homologous chromosomes, how they align on this meta phase one plate is independent and random from each other. And so this year concludes our brief introduction to the law of Independent Assortment, and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video