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Meiosis and mitosis have many similarities

Meiosis and mitosis have many similarities - chromatids...

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Meiosis and mitosis have many similarities. There are, however, several fundamental differences.  Compare Figure 1  (mitosis) with Figure 2  (meiosis). In meiosis:  In Prophase I,  homologous  chromosomes come together in  synapsis  and form  pairs called  bivalents  or  tetrads  (because there are four chromatids in the pair); each  bivalent has two chromosomes and four tetrads.  In Metaphase I, bivalents align randomly on the equatorial plane, which means that  each daughter cell has an equal chance of getting either the chromosome from the sperm  or one from the egg. In Anaphase I, the chromosomes separate, each with two chromatids, and move to  opposite poles; each of the two daughter cells is now haploid (  n ).  There is no S phase, and the chromosomes line up immediately in Metaphase II, their 
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Unformatted text preview: chromatids separate in Anaphase II and in Telophase II new cell walls form around the four haploid cells. (Events of the second division are similar to those of mitosis.) Synapsis in Prophase I is a decisive interval in determining the inheritance of the daughter cells. At this time, genetic recombination can occur; that is, daughter cells may receive combined traits of their two parents rather than simply the trait from one or the other. This is possible because the phenomenon called crossing over often occurs when the chromatids lie together—segments containing similar alleles break apart and rejoin to the corresponding segment of the opposite chromatid, thus mixing the traits from individual parents....
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