Reproduction, DNA, sexual & asexual

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 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 gonna 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'll 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 will find these long highly coiled a thread like structure and if you're assuming too 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 how 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 eat produce we will 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 you know and the body of the organism now that's something that will not talk about in great detail but let me just try and give you an overview so let me get rid of this pictures so to give you an overview DNA contains information or let me write it as a 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 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 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 will 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 that 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 a 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 an overview asexual reproduction happens from just one parent this reproduction is just one parent and so in this case you 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 DNA s 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 will 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 to 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 form 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 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 offsprings are similar but definitely not clones now of course at this point you may be having a lot of questions you might have 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 the 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 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