MITOSIS essays

MITOSIS essays Mitosis is the nuclear division in which the duplicated chromosomes separate to form two genetically identical daughter nuclei. It is also a phase in cell cycle in which the microtubular apparatus assembles, binds to the chromosomes, and moves the sister chromatids apart. Mitosis is the essential step in the separation of the two daughter genomes. Mitosis is subdivided into four stages, prophase, metaphase, anaphase, and telophase. Prophase is the first stage of mitosis characterized by the formation of a microtubule spindle along the future axis of division, the shortening and thickening of the chromosomes and their movement toward the equator of the spindle. The nucleolus also starts to disappear and the chromosomes condense. Metaphase is the second stage of mitosis. In this stage microtubules become organized into a spindle and the chromosomes come to lie in the spindles equatorial plane. When viewing this with a light microscope the chromosomes appear to arrange themselves in a circle along the inner circumference of the cell. Anaphase is the next stage of mitosis. In this stage the sister chromatids begin to separate and the daughter chromosomes move to opposite poles of the cell. Kinetochore microtubules shorten, polar microtubules elongate, and the cell begins to prepare for cytokinesis. The final stage of mitosis is telophase. In this stage the spindle apparatus disables, as the microtubules are broken down into tubulin monomers that can be used to construct the cytoskeletons of the daughter cells. The sister chromatids can now be called chromosomes because each has its own centromere. The chromosomes soon begin to uncoil into the more extended form that permits gene expression. Mitosis is now complete at the end of telophase. The eukaryotic cell has separated its replicated genome into two nuclei positioned at opposite ends of the cell. ...