Most one-celled organisims and most cells in multi-celled organisims reproduce and grow by mitosis. In this process, the nucleus divides to form two identical nuclei. ( A cell's cytoplasm divides soon after mitosis, creating two daughter cells with identical nuclei. Mitosis takes place in five stages or phases. The following is a presentation of mitosis and it's different steps. You can also watch a mitosis video.
Stage #1 Interphase
| This phase is called interphase, which occurs between one cell's nuclei division and the beginning of the next one. During interphase, the chromosomes are hard to see and the cell is busy growing and carrying on its normal activities. At some point in interphase, the chromosomes and the centrioles copy themselves. The original chromosome and its copy remain joined together by the centromere and are called sister chromatids. The cell can then start the next stage of mitosis. |
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Stage #2 Prophase
| In the stage of prophase, the chromosomes begin to curl up and become thicker and appear thread-like. At the same time, the cytoskeleton becomes like a net of fibers extending all over the cell. This network of fibers is called the spindle and each fiber is called an Astral Ray. ( Each centriole with its astral rays is referred to as a aster). The centrioles move apart along the fibers of the spindle until they reach opposite sides of the cell- the position of the centrioles at opposite sides of the cell become the sides of the spindle. Finally, the nuclear membrane starts to break up. |
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Stage #3 Metaphase
| In metaphase, the sister chromatids line up along the equator (or middle)
of the spindle, one chromatil on each side of the equator. Each chromatidis attached at
its centromere to at least one spindle fiber.
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Stage #4 Anaphase
| Here, the chromosomes divide and move to opposite sides of the cell.
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Stage #5 Telophase
| In telephase, the individual chromosomes uncurl and become hard to see
again. A new nucleus forms and the cell begins to divide.
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Cells after mitosis
| After the cell divides in telephase, each strand of genetic information
makes a duplicate of itself. Once the chromosomes contain the genetic information, the
cells can divide again.
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CELLS | CHROMOSOMES | DNA | QUIZ
