payment page
Mitosis
In unicellular eukaryotic organisms, mitosis is the only form of cellular reproduction. One round of mitosis yields two genetically identical cells. In bacteria, and other prokaryotic organisms, this process is called binary fission. This is classified as asexual reproduction because it does not require sex for the creation of new organisms. In multicellular organisms, like ourselves, mitosis only occurs in somatic cells, which comprise all cells in an organism excluding cells in the gonads.
Figure 4.02: Events of mitosis.
Cells that undergo mitosis duplicate their chromosomes, resulting in cells with two times their normal haploid or diploid numbers. Newly-synthesized chromosomes remain closely associated with their like-chromosome. These two identical chromosomes are called sister chromatids. Once duplicated, sister chromatids separate such that one copy of each chromosome lines up on opposite ends of the cell. The cell then pinches in the center until it breaks into two different cells. A nucleus then forms around the chromosomes in each cell to yield two cells with the same original number of chromosomes as the preexisting cell.
The specific events that occur during both mitosis are much more complex than described above and will be covered in depth in the following SparkNote on cell reproduction. This is just meant to be an introduction to the general concepts behind the process and as a means to introduce terms that will ease understanding of more complex explanations.
