Mitosis- Stages in Mitosis

• Prophase (1st stage): The DNA molecule coil, supercoil, gets shorter and thicker until it forms threads that are thick enough to be visible if they are stained. The nucleolus disappears and at this stage this spindle begins to form. The centrioles move away from each other to the opposite ends of the cell. The centrioles organize to form microtubules (a long, thin tubes of protein.)
• Metaphase (2nd stage): The nuclear membrane breaks down, then many of the microtubules attach themselves to the centromeres of the chromosomes. Each centromere of the chromosomes is grabbed by one microtubule on the other side. The microtubules pull in opposite directions on the centromere, bringing the chromosomes to lie at the equator of the cell.
• Anaphase (3rd stage): The centromeres split. The microtubules are still pulling on them, so the centromeres and the chromatids are pulled apart and moved to either end of the pole.
• Telophase (4th stage): The two groups of chromatids have arrived at the poles. They all have a complete set of chromatids. The microtubules that make up the spindle fibers, break down and disappear. A new nuclear envelope forms around each group of chromosomes. The chromosomes slowly uncoil and become thinner again.
• Cytokinesis (5th stage): The cytoplasm now divides and forms two new cells, each with a nucleus containing a complete set of chromosomes each with a centriole. The new cells are identical to each other and the parent cell.
• First Role of Mitosis:

  -Mitosis is involved in the repair of tissues in an organism. Ex: If you cut your skin, some of the cells at the edge of the cut will divide by mitosis two genetically identical cells that can cover the wound and join the cut edges together.
• The second role of mitosis:

  -Mitosis is involved in the immune response: When a lymphocyte comes in contact with a bacterium carrying antigens, the lymphocyte divides repeatedly by mitosis and produces a large population of genetically identical plasma cells. They secrete antibodies that lead to the destruction of bacteria.
• The third role of mitosis:

  -Mitosis is involved in asexual reproduction.