baisc question on meosis and mitosis

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junbumkim
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baisc question on meosis and mitosis

Post by junbumkim » Wed Apr 25, 2007 2:17 pm

so both meosis and mitosis are types of cell division.

cells in human will go through both meosis and mitosis; to produce sex cells, it would be meosis.

Before these process begins, chromosomes will condense to join by centromere. In meosis, we know that homologous chromosomes are joined by centromere...What about mitosis? Do chromosomes randomly condense? If so, isn't there a slightest chance that homologous chromosomes are joined even in mitosis?

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Poison
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Post by Poison » Wed Apr 25, 2007 2:39 pm

Sister chromatids(not homologous chromosomes)are held together with centromers in both meiosis and mitosis. In meiosis homologous chromosomes come closer to form tetrads. So crossing over occur between homologous chromosomes. Crossing over also occurs in mitosis. But as sister chromatids are identical, this does not cause any change.

PS: If you look for further info, crossing over between sister chromatids are used to detect carsinogen substances. It is called SCE test. You can easily find about it if you are interested.
Last edited by Poison on Wed Apr 25, 2007 2:42 pm, edited 1 time in total.
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Post by Darby » Wed Apr 25, 2007 2:40 pm

Homologous chromosomes aren't joined at the centromere (unless your phasing is unusual).

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