One of the most basic cycles every student of Biology must know is mitosis. It is the process in which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two daughter nuclei. (Rubenstein & Wick, 2008) It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two daughter cells containing roughly equal shares of these cellular components. (Wikipedia)
It has four stages: Prophase, Metaphase, Anaphase & Telophase. Other books or sources would give additional stages like Pre-prophase, interanaphase, etc. but I’ll be focusing on the basic stages for now.
Replicated DNA condense into dark and dense bodies called chromosomes (chromo = colored, soma = body). Each chromosome is actually a pair of chromatids held together by a centromere. Then the centrioles separate from each other and move towards the poles of the cell. They then spin mitotic spindles as they move. These spindles will provide “scaffolding support” for the attachment and movement of the chromatids during the later stages of mitosis. At the end of prophase, the nuclear membrane and nucleolus have disappeared.
This is short stage wherein the chromosomes cluster together and align at the middle of the mitotic spindle so that a straight line of chromosomes can be seen.
During this stage, the centromeres that have held together the pair of chromatids detach and separate from each other. The chromatids, now called chromosomes again, move apart from each other and towards the end of each pole. When the chromosomes reach the poles of the cell, anaphase is over.
At this stage, the chromosomes have reached the poles completely and begin to uncoil to become chromatid threads again. The nuclear membrane begins to reform and surround each of the new nucleus. The spindle breaks down and the rest of the cell splits in two via cytokinesis which forms two identical daughter cells.
To wrap up, here’s a video of the mitotic cycle to help you review.
Mitosis. (2009, June 30). In Wikipedia, The Free Encyclopedia. Retrieved 01:23, June 30, 2009, from http://en.wikipedia.org/w/index.php?title=Mitosis&oldid=299423834
Rubenstein, Irwin, and Susan M. Wick. “Cell.” World Book Online Reference Center. 2008. 12 January 2008, from http://www.worldbookonline.com/wb/Article?id=ar102240
Video created by MsStokesBio