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Anaphase
The fourth stage of mitosis during which sister chromosomes are separated and pulled to opposite ends of the cell by kinetochore microtubules.
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Contractile ring
A ring of protein filaments that encircles the region of the metaphase plate in a dividing cell. Responsible for pinching the cell until it separates into two independent cells.
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Cytokinesis
The final part of M Phase, during which a cell with duplicated contents splits into two independent cells.
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Kinetochores
Sites on replicated, bound sister chromatids to which microtubules bind, thereby becoming kinetochore microtubules.
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M phase
The name given to the five separate steps of mitosis and the final cleavage of the cell in cytokinesis.
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Metaphase
The third stage of mitosis during which kinetochore microtubules* align sister chromatids along the metaphase plate at the center of the cell.
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Metaphase plate
An imaginary line found half way between the two mitotic spindle poles on which chromosomes align during metaphase.
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Microtubule
One of three protein components of the cytoskeleton. Long, cylindrical structures approximately 25 nanometers in diameter. Extend from the centrosome to all parts of the cell, forming tracks on which organelles can travel within the cell. Microtubules can be either kinetocore microtubules or non-kinetocore microtubules. Kinetocore microtubules bind to sister chromatids during mitosis. Non-kinetocore microtubules are broken down into two further categories: polar microtubules and astral microtubules.
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Mitosis
The five-step process by which a cell separates replicated chromosomes before cytokinesis creates two identical daughter cells from one original cell. The five steps of mitosis are: prophase, prometaphase, metaphase, anaphase, telophase.
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Mitotic spindle
A complex of microtubules that form between opposite poles of a cell during mitosis. Serve to separate and move sister chromatids to opposite ends of the cell for division.
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Prometaphase
The second stage of mitosis during which the nuclear envelope disassembles and microtubules gain access to chromosome kinetochores.
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Prophase
The first stage of mitosis, during which visibly dark, condensed chromosomes are found in the nuclear envelope.
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Telophase
The fifth and final stage of mitosis before cytokinesis; in telophase, the nuclear envelope re-forms around separated sister chromatids and kinetochore microtubules disappear. Cell elongation and decondensation of chromosomes also occur.
