The Stages of Cell Division

 

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During cell division many changes occur. Cell division is often only described as the mitotic phase of a cell, but mitosis is a series of stages not just one. It begins with prophase, which is when microtubules in the cytoplasm begin to form the spindle. At the same time, the chromosomes in the cell become compact, the nucleoli disappear, and the chromosomes migrate to the poles of the cell. The spindle microtubules and chromosomes meet in the prometaphase. By the time the spindle is completely formed, metaphase begins. During this phase the chromosomes line up in the middle, or equator, of the cell. When learning about the process of cell division, many people associate the word "middle" with metaphase because it is easy to conclude that when all chromosomes are in the middle of a cell there is no doubt that it has to be in metaphase. The chromosomes spit up and are pulled to opposite sides of the cell, which begins the anaphase stage. Chromosomes on both sides become enveloped with another nuclear envelope, making a nucleus on both sides. The spindle formed in prophase disappears, and cytokenesis begins. Cytokenesis divides the cell into two seperate cells and those cells begin the process all over again. Like Virchow's principle states, every cell comes from another cell.



Sources: Class Notes-Chapter 8: The Cellular Basis of Reproduction and Inheritance

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