Mitosis
The Dance of the Chromosomes
When a human cell divides, its 46 chromosomes must be copied, or replicated, and each of the two new cells must receive only one copy of each chromosome. Mitosis (from the Greek mitos = thread) is the process that sorts the genetic material into two new nuclei and ensures that both contain exactly the same genetic information.
Embryos, babies and children grow using mitosis, and mitosis occurs all the time in our adult bodies, as new cells replace old ones--such as worn-out blood cells or skin cells injured by cuts or burns.
Though mitosis is a smooth continuous process, biologists have divided it into several stages.
Interphase Interphase is the cell growth phase in which a cell increases in size and carries out activities that support the organism. It is technically not a part of mitosis. Near the end of this phase, the chromosomes of the cell duplicate in preparation for cell division. By the time a cell is ready to divide, there are two copies of each chromosome (the sister chromatids.) |
Prophase |
Metaphase
|
Anaphase The chromosomes separate. One copy of each chromosome is pulled to each end of the cell by the spindle fibers |
Telophase The cell membrane begins to pinch the cell in two to divide the cytoplasm. A new nuclear membrane forms in each daughter cell. The daughter cells contain the same genetic information as was found in the original cell and as each other because the chromosomes in each cell are the same. |
Interphase for the two new cells begins The chromosomes uncoil and the cells begin to grow. Images from http://www.biodidac.bio.uottawa.ca |
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