Two major changes must occur
1) the condensation of the chromosomes
2) assembly of microtubules to form the spindle
Chromosomes consist of chromatids which become replicated during the S phase of the cell cycle and are joined together by a constricted area common to both chromatids. This region of attachment is known as the centromere. Disk-shaped protein-containing structures called kinetochores are sites to which the microtubule spindle fibers attach.
Spindle formation includes polar fibers and kinetochore fibers
Four stages of mitosis - nuclear division
Prophase -
Metaphase - chromosomes align at the equatorial plate.
Anaphase - individual chromatids are separated. The two sets of newly separated chromosomes are pulled by spindle fibers toward opposite poles of the cell.
Telophase - the nulcear envelope reappears. Two new nuclei are present. Chromosomes again begin to decondense becoming diffuse once more.
The spindle apparatus disappears.
Plasma membrane begins to pinch (cytokinesis).
Cytokinesis - cytoplasmic division - usually accompanies nuclear division- Mechanisms involves actin filaments acting as "purse strings" being pulled together.
