Meiosis, Part Two

Hana Halling

Prophase II- During the second part of meiosis, in prophase II, the nuclear seal in broken, allowing for the new spindle to form and chromosomes to condense. Also, the centrioles duplicate at this point, separating into their separate centrosomes. This takes place by the two orignial centrioles separating, and then a new centriole forming perpenidicular to these two. Although none of the DNA is replicated during this time, it is an important step in the preparation for this replication.

Metaphase II- In Metaphase II, the spindle fibers, which developed in Prophase II, attach themselves to the chromosomes. Also, the chromosomes and homalogue pairs move to the center of the cell and line up. This center section is called the equatorial plate.  During this phase is when the chromosomes prepare to combine and create the daughter chromosomes.

Anaphase II- At this point, the centromeres separate. Also, the four chromatids separate, each at separate sides of the spindle device. This allows the separated chromatids to become their own chromosomes. The Anaphase is when chromosomes are actually formed, and is therefore a critical part of the entire process of meiosis.

Telophase II- During the telophase, each set of chromosomes receive their own nuclear envolope surrounding them. Cytokinesis also happens at this time. This is the process in which four new daughter cells are produced. These daughter cells then receive their own set of haploid chromosomes. The end product of the entire, complicated, meiosis cycle is seen at this time, as the four new cells appear, with their own chromosomes. 

Sources- Holt Science Textbook

http://www.phschool.com/science/biology_place/biocoach/meiosis

 biology.about.com/library/weekly