Mitosis/ cell division

atlanta.
Note by , created almost 6 years ago

GCE/AS level Biology (Mitosis) Note on Mitosis/ cell division, created by atlanta. on 12/02/2013.

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atlanta.
Created by atlanta. almost 6 years ago
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Page 1

Interphrase stage - This is when the cell is not dividing and the chromatin is not visible, DNA are replicated. Once the DNA is replicated these are then attached by a centromere, the two identical strands are called chromatids. Prophase - This is when the mircotubules and chromosomes become visible. Chromosomes are too small to see, so they have to supercoil, this then makes them get shorter and thicker. The nucleolus disappears.  Metophrase - The centromeres line up at the equator. This is done by microtubules attaching themselves to them. The mircotubules pull on either side so they line up on the equator.Anaphrase - This is when the centromeres start to split from one another, the chromatids then split away from each other. Telophrase - Two groups of chromatids have now arrived at the poles. The spindle then disappears, a nuclear membrane then forms around the chromosomes.  They then uncoil and become thinner againCytokinesis  - The cytoplasm then splits. The new cells are genetically identical to each other and to the original. 

Meiosis

As mitosis produces diploid chromosomes. Meiosis undergoes all of the stages in mitosis however this instead of 46 chromosomes, the chromosomes are haploid with 24 chromosomes.Haploid cells have one copy of each chromosome. 



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