Meiosis

Meiosis isbiological cell division processeukaryotes by whichdiploid parent cell produces four haploid daughter cells. It consiststwo cyclesnuclear division, usually accompanied by cell division (especiallymulticellular forms, where itgenerally usedproduce gametes (gametogenesis), preceded by DNA replication.

The mechanistic differences between mitosis, which produces somatic cells,meiosis,best understood by considering mitosis first. (All jargon usedthis articledefined inarticle on mitosis.) Duringmitotic division, chromosomesduplicated but remain closely aligned,these twin copiescalled sister chromatids. Note that diploid cells have two setshomologous chromosomes. DNA replication generates sister chromatids from each chromosome,ininterval between DNA replicationcell division,cell bears four copieseach chromosome. At metaphase, sister chromatids align onmitotic spindle. At anaphase, these sister chromatids separate, each migrating toward an opposite pole ofspindle. The two new cells that result bear one copyeach homologous chromosome.

A meiotic nuclear division consiststwo stages, called meiosis Imeiosis II. It starts withcell insame state as doesmitotic division. However,alignmentchromosomesprophasedifferent. Homologous chromosomes join into tetrads (so called because each tetrad contains four chromatids), andtetrads line up onmetaphase plane. During prophase I (the prophasemeiosis I), various phenomena uniquemeiosis may occur, such as crossing over. During metaphase I,tetrads line up onmetaphase plate or equatorial plate. During anaphase I, theypulled apart into their constituent homologous chromosomes.
Meiosis IIidenticalmitosis.

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Meiosis isfigurespeech. See meiosis (figurespeech)