Saturday 20 August 2011

Bio 3 : Stage of Meiosis



1*.Meiosis stages:
   ~ Meiosis comprises of  two successive nuclear divisions with only one round of DNA replication.

2) 4 stages can be described for each nuclear division :
 a. Interphase : Before meiosis begins, genetic material is duplicated.

 b. First division of meiosis :

*Prophase1 : Duplicated chromatin condenses. Each chromosome consists of two, closely     associated sister chromatids. Crossing-over can occur during the latter part of this stage.
*Metaphase 1: Homologous chromosomes align at the equatorial plate.
*Anaphase 1: Homologous pairs separate with sister chromatids remaining together.
*Telophase 1 :Two daughter cells are formed with each daughter containing only one chromosome of the homologous pair.

3) Second division of meiosis : Gamate formation
~Prophase 2 : DNA does not duplicate.
~Metaphase 2 : Chromosomes align at the equatorial plate.
~Anaphase 2 : Centromeres divide and sister chromatids migrate separately to each pole.
~Telophase 2 : Cell division is complete. Four haploid daughter cells are obtained.





 



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