Mitosis and meiosis are two different types of cell division. Mitosis occurs in somatic cells and results in two identical daughter cells with a diploid (2n) number of chromosomes. This process is essential for growth and repair in the body. On the other hand, meiosis occurs in germ cells and produces four non-identical gametes with a haploid (n) number of chromosomes. These gametes, such as sperm and egg cells, are crucial for sexual reproduction and genetic diversity. Created by Sal Khan.
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- Is it possible for a gamete to go through mitosis after it went through meiosis?(25 votes)
- A single gamete will not go through mitosis. But after fertilization, the zygote will have numerous mitotic divisions and specialization of cells in to specialized tissues(35 votes)
- If our germ cells can do mitosis and meiosis, then when do they know when to use what?(14 votes)
- So is mitosis Asexual Reproduction, and Meiosis Sexual Reproduction?(8 votes)
- Not quite — reproduction is usually† used to mean the production of new organisms. Mitosis and meiosis are about the production of new cells.
Mitosis is the eukaryotic method for producing new cells with the same genetic composition as the mother cell.
For single celled eukaryotic organisms (e.g. yeasts) mitosis does result in asexual reproduction, but this not usually true in multicellular eukaryotes.
Thus, mitosis is one way§ that asexual reproduction can occur, but only when the cell is an entire organism.
In contrast, meiosis is a method for producing new cells with half the number of chromosomes that were found in the mother cell.
(Genetic recombination also takes place during meiosis.)
These cells typically become gametes in animals (other forms of life are more complicated‡) that then fuse to form zygotes that represent the next generation for that species.
This whole process is sexual reproduction, so it would be true to say that meiosis is a part of sexual reproduction.
For more information on reproduction:
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†Note: Not all sources make this distinction.
§Note: Other forms of asexual reproduction include budding and binary fission (the most common type of cell division in prokaryotes).
‡Note: For information on other modes of sexual reproduction:
- Justify why only gamete cells go through meiosis.(4 votes)
- Meiosis is the process of halving the amount of chromosomes to prepare for sexual reproduction. Since gametes are involved in sexual reproduction, their chromosome number must be halved since the male gamete will fertilize the female gamete, completing the diploid number.(17 votes)
- Do sperm and egg cells (once made) undergo mitosis to increase number?(3 votes)
- correct! once they fuse together theyre basically a normal cell which, in order to multiply, has to undergo mitosis(6 votes)
- Does mitosis have homologous pairs too?(3 votes)
- The chromosomes that make up the homologous pairs are present in diploid cells, but each member of a homologous pair of chromosomes behaves more-or-less independently in mitosis — i.e. since they don't pair up they just look like separate chromosomes.
Does that help?(5 votes)
- So basically mitosis is cell division and meiosis is the sexual reproduction of cells? I mean I watched the whole video and I just wanted to clarify.(3 votes)
- Kind of, but not quite. Mitosis is the process of a cell making an exact copy of itself. The end result is two daughter cells that are identical to each other in every way, essentially "clones" of each other, each with a full set of genetic information necessary for life. Meiosis, on the other hand, goes through two splitting processes to result in four gametes, also known as sex cells (sperm and eggs). The difference here is that each of the resulting gametes has only half of the chromosomes of the original cell, and thus only half of the genetic information for life.
I hope this helped!(5 votes)
- When are centromeres duplicated for meiosis II? I know they are duplicated in the interphases for mitosis and meiosis I, but if meiosis II does not have a interphase before its process, I wonder when..(3 votes)
- I don't understand why can't the cell undergo fertilisation when it first become n from 2n? Like why does it have to form four n's and then fertillise?(5 votes)
- the n is the number of chromosomes in the cell. so in the case of humans, our diploid (2n) number is 46 which is 2 homologous pairs of 23 chromosomes, which is what we have in most of our cells. gamets have a haploid (n) number of chromosomes which is just the 23.(1 vote)
- When does the chromosomal crossover occur? Late prophase or Metaphase?(2 votes)
- Paired homologous chromosomes crossover while in synapsis, this happens during early prophase 1. By late prophase 1, the synaptonemal complex has disassembled and the homologues are only linked at places called chiasmata (singular, chiasma) where crossover occured. This all occurs before metaphase 1 begins.(5 votes)
- [Voiceover] Before we go in-depth on meiosis, I want to do a very high level overview comparing mitosis to meiosis. So, in mitosis, this is all a review, if you've watched the mitosis video, in mitosis, we start with a cell, that has a diploid number of chromosomes. I'll just write 2n to show it has a diploid number. For human beings, this would be 46 chromosomes. 46 for humans, you get 23 chromosomes from your mother, 23 chromosomes from your father or you can say you have 23 homologous pairs, which leads to 46 chromosomes. Now after the process of mitosis happens and you have your cytokinesis and all the rest, you end up with two cells that each have the same genetic information as the original. So you now have two cells that each have the diploid number of chromosomes. So, 2n and 2n. And now each of these cells are just like this cell was, it can go through interphase again. It grows and it can replicate its DNA and centrosomes and grow some more then each of these can go through mitosis again. And this is actually how most of the cells in your body grow. This is how you turn from a single cell organism into you, or for the most part, into you. So that is mitosis. It's a cycle. After each of these things go through mitosis, they can then go through the entire cell cycle again. Let me write this a little bit neater. Mitosis, that s was a little bit hard to read. Now what happens in meiosis? What happens in meiosis? I'll do that over here. In meiosis, something slightly different happens and it happens in two phases. You will start with a cell that has a diploid number of chromosomes. So you will start with a cell that has a diploid number of chromosomes. And in it's interphase, it also replicates its DNA. And then it goes through something called Meiosis One. And in Meiosis One, what you end up with is two cells that now have haploid number of chromosomes. So you end up with two cells, You now have two cells that each have a haploid number of chromosomes. So you have n and you have n. So if we're talking about human beings, you have 46 chromosomes here, and now you have 23 chromosomes in this nucleus. And now you have 23 in this nucleus. But you're still not done. Then each of these will go through a phase, which I'll talk about in a second, which is very similar to mitosis, which will duplicate this entire cell into two. So actually, let me do it like this. So now, this one, you're going to have four cells that each have the haploid number that each have the haploid number of chromosomes. And they don't all necessarily have the same genetic informatioin anymore. Because as we go through this first phase, right over here of meiosis, and this first phase here you go from diploid to haploid, right over here, this is called Meiosis One. Meiosis One, you're essentially splitting the homologous pairs and so this one might get some of the ones that you originally got from your father, and some that you originally got from your mother, some that you originally got from your father, some that you originally got from your mother, they split randomly, but each homogolous pair gets split up. And then in this phase, Meiosis Two, so this phase right over here is called Meiosis Two, it's very similar to mitosis, except your now dealing with cells that start off with the haploid number. It's important to realize that meiosis is not a cycle. These cells that you have over here, these are gametes. This are sex cells. These are gametes. This can now be used in fertilization. If we're talking about, if you're male, this is happening in your testes, and these are going to be sperm cells If you are female, this is happening in your ovaries and these are going to be egg cells. If you a tree, this could be pollen or it could be an ovul. But these are used for fertilization. These will fuse together in sexual reproduction to get to a fertilized egg, which then can undergo mitosis to create an entirely new organism. So not a cycle here, although these will find sex cells from another organism and fuse with them and those can turn into another organism. And I guess the whole circle of life starts again. But it's not the case with mitosis where this can keep going and going, going. This cell is just like this cell, while these sex cells are differeent than this one right over here. Now, where does this happen in the body? We've talked about this in previous videos. These are your somatic cells right over here. These are the ones that make up the bulk of your body, somatic cells. And where is this happening? Well, this is happening in germ cells, As we mentioned, if you're male it's in your tesis and if you're female it's in your ovaries. And germ cells actually can undergo mitosis to produce other germ cells that have a diploid number of chromosomes, or they can undergo meiosis in order to produce sperm or egg cells in order to produce gametes.