Meiosis and Mitosis

[Zebra]

I know this is gonna sound retarded but can someone outline the differences...

[Greatness]

Meiosis is cell division in gametes and mitosis is normal cell division.

[Zebra]

Meiosis is cell division in gametes and mitosis is normal cell division.

well, now that's established, what's the deal with meiosis diving into 4 cells whilst mitosis only divides into 2?

[Greatness]

Hmm youre really testing my memory here!
im not entirely  sure but i think it's because in meiosis, the main cell breaks up into 2 daughter cells and those 2 divide into another 2 which makes the 4 cells. then these guys have like 1 of each DNA molecule or something.... sex cells need to undergo meiosis because if they join together like normal cells they will double up on the no. of chromosomes.

someone clear this up lol

[Kaille]

Mitosis:
only one division
2 identical cells produced
no crossing over
occurs in somatic cells
one diploid cell will divide into 2 identical diploid cells
Used for: repair, replacement

Meiosis:
two divisions
four cells produced that are genetically different to their parent cell (this is because they only take half of their parents dna and also because of crossing over)
occurs in gonads to produce gametes
one diploid cell will divide into four haploid cells (only has a single set of unpaired chromosomes)
Used for: producing gametes- swarley is right, during fertilisation, the gametes (sperm and egg- both have 23 chromosomes each) fuse to produce a zygote containing the full diploid set of chromosomes.

hope this helps

[Abdulhai]

Kaille you beautiful human, thanks.

[scar]

Before either Meiosis or Mitosis the cell makes an entire copy of the DNA.  So if you want to finish with the same amount as at the start you divide once (mitosis = 2 cells)  If you want to finish up with just half the amount in each cell you have to do it twice! (Meiosis = 4 cells)

[nolan91]

Mitosis is the asexual division of cells that produce two, more or less, identical diploid (full set of chromosomes) cells. Meiosis is the sexual division of cells into four haploid (half set of chromosomes) cells. There are also two divisions in meiosis: meiosis I and II. Meiosis I produces two haploid cells and is also where crossing over occurs. Meiosis II is simply mitotic division of two haploid daughter cells into four haploid daughter cells.

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