Biology:Cell Division and DNA: Mitosis and Meiosis
Cell Division: Mitosis and Meiosis
Web resources: Mitosis
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Mitosis: Tutorial
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Mitosis and Meiosis - a brief guide
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Videos: Mitosis and Meiosis
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Video: DNA Replication
Web resources: Meiosis
Summary of Stages:
- Interphase
- G1 phase
- S phase (DNA material is replicated)
- G2 phase
- Meiosis I (Reduction Division: Halves chromosome number)
- Prophase I
- Metaphase I
- Anaphase I
- Telophase I
- Interphase (DNA material does NOT replicate)
- Meiosis II (Equational Division: Produces 4 daughter cells from 2)
- Prophase II
- Metaphase II
- Anaphase II
- Telophase II
- There is no way to predict which set of chromosomes will end up
in which daughter cell. It is only certain that, unless something
goes wrong, each daughter cell will have one of each chromosome.
- This is called independent assortment. In humans, because
there are 23 pairs of chromosomes, the number of possible assortments is:
2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2 = 8,388,608!
- Any one of these assortments can combine with any one of
the 8,388,608 combinations of his/her partner!
- But, during meiosis, chromosomes exchange parts of their
genetic material with the corresponding regions on their homologous
chromosome. This process is called crossing over and it makes the
number of possible combinations nearly unlimited.
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