Tuesday, September 30, 2008

What are the 8 stages of mitosis in order?

Mitosis is the production of two identical "daughter" cells from one cell. Generally, mitosis is considered to have fewer steps; in order to have eight stages you must include interphase and its divisions. Interphase, in which the cell spends most of its time and is when it is doing whatever job that cell type is specialized for, is not usually counted in the stages of mitosis. However, since the DNA is duplicated during interphase in preparation for mitosis it could technically be counted. 


Interphase: 


  1. G1 (Gap 1) phase. Normal cell functioning

  2. S (Synthesis) phase. DNA is duplicated.

  3. G2 (Gap 2) phase. Cell continues to grow in preparation for mitosis.

Mitosis:


  1. Prophase--Chromatin condenses into chromosomes, and centrioles move to opposite sides of cell.

  2. Metaphase (sometimes further divided into Prometaphase and Metaphase)--nuclear membrane finishes dissolving. Chromosomes line up at middle of cell, and microtubules attach at kinetochores.

  3. Anaphase--Chromosomes separate at kinetochores; one of each pair moves to either side of cell.

  4. Telophase--Chromosomes reach opposite sides of cell, and new nuclear membranes begin to form around them.

  5. Cytokinesis--formation of two new cells, with two new cell membranes complete.

There is a LOT more to all of this, and there are differences for animal and plant cell division, but the basics are the same. Bacterial cells also undergo mitosis for reproduction, but as they do not contain nuclei there are even more differences from the above (see second link below).

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