Differences between Mitosis and Meiosis
Let's look at the chromosomes , their number and shape and see what happens to them in the two types of cell division?
| In somatic cells : mitosis
A somatic cell is any cell of an organism which is not a germ cell |
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| Mitosis is a simple, single cell division
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During metaphase, chromosomes can be seen to have two chromatids . The separation occurs between chromatids of the same chromosome. |
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| During metaphase of the cell division, the chromosomes are all situated at the equator, but they are not touching each other. Thus, they can't exchange any material. | |
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Then, the chromatids separate. This is the end of mitosis |
In germ cells : meiosis
Germ cells are cells that divide into gametes
Meiosis is a more complex process , with two cell divisions.
During the first stages of meiosis, the chromosomes of the same pair are
very close to each other.
The chromatids of a chromosome exchange material with a chromatid of its
matching pair. That is what is illustrated above. This event is called
"crossing over".
Note how different the chromatids are now.
Locate
a chromosome,
a chromatid,
a pair of chromosomes.
The chromosomes separate at this stage. What is different from mitosis at
this stage?
Both cells divide again. This time the chromatids separate.
About Meiosis
How many cells do we have at the end?
How many chromosomes in each cell?
Do we have pairs?
What will happen to these cells?
What are the advantages of meiosis?
Try to think of the mechanism of reproduction and the events occuring then.