Sexual and Asexual Reproduction

by Jason Amores Sumpter
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Hi. In this lesson will be talking about animal reproduction, which often is going to be sexual reproduction, which is when two organisms combine their genetic information, usually through the fusion of GAM. It's now gametes are formed from my oh sis. And these are going to be, uh, cells that have just one copy of each chromosome from the parent making them hap Lloyd. Now, if this sounds an unfamiliar, I recommend you go check out our videos on my Asus and sexual life cycles. Now, male gametes are no nas sperm and female gametes air. No nas eggs. Male gametes usually are smaller and motile, meaning they can move themselves. They can propel themselves. Female gametes tend to be larger and non motile, meaning they can't propel themselves. Now we call the fusion of sperm and egg fertilization, and this will form a zygote. So we will get a zygote from fertilization and that zygote is going to be deployed, meaning it will have two copies of each chromosome one from each parent, thanks to those gametes, each being half Lloyd. Now, some organisms reproduce through a sexual reproduction, and this is when offspring arises from a single organism and it on. Lee receives genes from that parent. Now there are a few ways this can occur. One is butting, which is when on organism will kind of grow off of its parent and break off when it becomes mature. You can see that happening in these yeast cells here. Yeast are, um you know, eukaryotic organisms, and they reproduce by budding. You can see this parent cell has this bud growing off of it. So does this one. When these buds air mature, they will literally break off from their parents sells. This also occurs in the animals hydra. They also reproduce through budding. Now fission is when an organism divides into two or more parts. And this is how, for example, bacteria reproduce. Uh, this is known as binary fission and bacteria, and as you can see, it's going to lead to to genetically identical organisms. Now parthenogenesis is a very interesting type of a sexual reproduction because it's when growth and development occurs without fertilization. You see this in, for example, some species of lizards which are going to be all female, and we'll just grow and develop offspring in the app without any fertilization and those offspring will, of course, be female. So you might be wondering, what's the point of sexual reproduction? Because it's mawr energy intensive, and it's less efficient than a sexual reproduction. E. Look at this little graphic behind me. A sexual reproduction like we can see here, is going to lead to much greater increases in the population size. So what's the advantage for doing it this way? You can't increase the population size nearly as efficiently. It also requires two organisms just to produce one new offspring. Or, in the case of some organisms, you'll produce multiple offspring. But you get my point. It requires to parents to get together to generate any offspring. So what's the point? Well, one explanation for this is known as the Red Queen. Hypothesis and theory. Idea is essentially genetic diversity. Organisms that reproduce a sexually don't, um, have a harder time introducing genetic diversity. Let's say they have to come up with other mechanisms to do that. Aside from these a sexual reproduction methods, sexual reproduction naturally has naturally confers genetic diversity to the population. This is important because the Red Queen hypothesis says that organisms have to constantly and adapt and evolve to compete with the posing organisms. This idea comes from a quote from Alison Wonderland from the character known as the Red Queen. When Alice is talking to her, she says that you know where I come from, not Wonderland. When you run, you get somewhere. You know, when you move, you actually get to some place, and the red queen says Now, here you see, it takes all the running you can do just to stay in the same place. And that is why this is termed the Red Queen hypothesis. It's because organisms have to constantly be running right, adapting and evolving, which is why sexual reproduction is favored because it introduces genetic diversity that promotes that adaptation and evolution. And this is necessary because they have to compete with all the other organisms around them that are also constantly adapting and evolving. With that, let's go ahead and flip the page