 Well, let's talk about how reproduction works at a cellular level. What I mean to say is if an organism wants to reproduce, basically it has to make new cells because all living things are made of cells, right? But the question is if a human beings make new cells while reproducing, how does it grow into a new human being itself and not say a cat? When monkeys make new cells while reproducing, how does it grow into a monkey and not cat? So that's the basic question we're going to try and figure out in this video. All right, so how do we do it? Well, the answer lies in a molecule called the DNA. It's a very famous molecule. You may have already heard about it. And if you're wondering what's the full form of this DNA, well, it stands for deoxyribonucleic acid. So it's basically a molecule, a long, long molecule. Now, since we don't want to worry too much about its chemical structure and composition, let me hide this. We don't have to worry too much about its chemistry part. But let's try and understand how DNA helps, you know, how DNA helps in reproduction. Let's talk about that. So first, let's start with where do we find DNA? Well, if we take any animal cell, let's say this is a typical animal cell, it will find all its parts like the mitochondria, the ectoplasmic reticulum, the cytoplasm and all that stuff. You'll have the nucleus and if you look inside the nucleus, that's where you'll find these long, highly-coiled, thread-like structure. And if you're zooming to that, you will see that it's actually made up of two strands wound together like this. We call it the double helix. And this is your DNA. And guess what? It's the DNA which contains the blueprint to build the entire body, which means all the instructions necessary to build a specific body is found in the DNA itself. So the human DNA, for example, if you look at a human cell, it'll contain the human DNA. It'll have the information of how to build a human body. Monkey DNA will have the information to build a monkey body. Dog DNA will have the information to build a dog body and so on and so forth. So basically, when we reproduce, the cells are using the information from the DNA to build the right body. And that's why when humans reproduce, we will make new humans itself. And when dogs reproduce, they will make new dogs itself and not cats. Now of course, you may be very curious to learn how does this whole thing work out? Like what kind of information is present on the DNA and how is it that that information is used by the cells to build the body of the organism? Now, that's something that we'll not talk about in great detail. But let me just try and give you an overview. So let me get rid of these pictures. So to give you an overview, DNA contains information or, let me write the last recipe. DNA contains the recipe to build something called proteins. Proteins, what are proteins? Proteins are again just molecules, molecules which are super essential to build any living body. Okay, for example, you might know that proteins are essential to building muscles. So the thing about proteins is that there are various kinds. And so if you want to build a human body, you need a particular set of proteins. If you want to build a cat body, you need a different set of proteins. And therefore, a human DNA will contain recipe to build the proteins required for the human body. So the cat DNA will contain the recipe to build proteins for a cat body. That's basically how DNA helps the cells in building the proteins required for a particular body and eventually by building more and more proteins that entire body can be built. And just one small side note. The DNA is very, very long. And so it's usually coiled. It has many, many, many, many coils so that it can fit inside the nucleus of the cell. And this coiled version of the DNA is what we call the chromosomes. Okay, again, I'm not gonna write down this word chromosome because we'll talk about them in great detail in other videos. So just remember that a coiled version of DNA is what chromosomes basically are. Because you'll keep hearing this term called chromosomes, okay? Anyways, now the question is, what does this all mean for reproduction? So like we said, in reproduction, the cells need to be able to make a copy of itself, right? And now we know that DNA is super important. This means in order to successfully able to reproduce, the cell needs to be able to make a copy of its DNA. That is the most important thing for reproduction. So let me just write that down. So for reproduction or to reproduce, for reproduction, what is needed? What is the most important thing needed at the cellular level? The DNA should be able to make a copy of itself. So I'm just gonna write the DNA copy. So the way it works is, let me just draw another cell over here. When this cell is ready to make a copy of itself, its DNA will first make a copy. It has the machinery, the cell contains the machinery to make copies of DNA. So the DNA will make a copy of itself. Then all these other organelles will also make a copy of themselves. And once all the copies are made, the cell will then split into two new cells. Each one containing the same DNA. And then that cell can further split into many, many, two more cells. And this can split into two more cells. And that's how more and more and more and more and more cells can be made. And eventually, using the information from the DNA, proteins can be made. And eventually, this whole single cell can has the ability to grow into an organism, depending upon what kind of DNA is present inside of it. And finally, based on how the DNA is formed in the offsprings during reproduction, we can classify reproduction into two kinds. We have something called as asexual reproduction. And we have something called sexual reproduction. Again, just to give you an overview, because we'll talk about them in great detail in the future videos. Just to give you an overview, asexual reproduction happens from just one parent. This reproduction is just one parent. And so in this case, you'll find that the DNA of the cells of the offspring or the child will be identical to the DNA of the parent. Because they have identical DNAs, the offspring will grow into a new individual which will look exactly the same as that of the parent. And as a result in asexual reproduction, we'll find that the offsprings are clones of the parent. That's what we will say over here. Offsprings are clones of the parents because the cells of the offsprings and the cells of the parent have the same DNA. Okay. In contrast, if you look at sexual reproduction, what we will find now is that there are two parents involved in reproduction. Like in human beings, a male and a female. So opposite sexes, two parents of opposite sexes, male and female. So over here, what happens is the DNA of the male and the female combine together to form a new cell. So the new cell formed during reproduction will have a combination of the male and the female DNA. And as a result, when that grows into a new individual being, new organism, it will not be identical to either of the parents. You understand why? Because the DNA is not the same as the male, neither the male nor the female. It's a combination. And that's why they will look similar to the parents, of course, but they will not be exact clones. And since humans undergo sexual reproduction, we can see this in ourselves. You and I, we look similar to our parents. We have characteristics similar to our parents, but we don't look like clones of our parents at all. And so over here, here we will see that the offspring are similar, but definitely not clones. Now, of course, at this point, you may be having a lot of questions. You might, you might ask, like, what do we mean by DNA gets combined? What is the meaning of that? How does it happen? And why does it even happen? Why do we even need sexual mode of reproduction? Why go through all that trouble? Well, we'll talk about, you know, we'll talk about them in great detail, of course, in the future videos. But that's it for this video. So let's quickly summarize. What did we learn? We learned that the DNA is the blueprint to building any organism, whether it is humans or cats or dogs, any species you want. The information to building the body is contained in the DNA. Where do you find the DNA? DNA is found in the nucleus. It's highly coiled inside the nucleus, and that coiled version of DNA is what we call the chromosomes. And what does a DNA do? DNA basically contains recipes to build proteins. Different DNA will have different recipes to create different proteins, which will create different structures, meaning different organisms. And so for reproduction, it's super important that DNA is able to make a copy of itself. So every time we want to reproduce, the DNA makes a copy of itself. And so every time a cell needs to make a copy of itself, the DNA first has to make a copy of itself, and then all the other organelles make a copy of itself, and that's how we will get new copies of cells. And then finally, if we have just one parent involved in reproduction, we will say it's an asexual reproduction, where the offsprings are clones of the parents because they have the exact same DNA as that of the parent. And if we have two parents involved in reproduction, we call sexual reproduction. Over here, the offsprings are not clones. They look similar, but not exactly the same because their DNA is a combination of the DNA of the father and the mother.