11/6 Cell Division cont.

(Chapters 9-10)

II. Mitosis- Cyclic (never stops). The Cell Cycle:
    A. G1 Phase- ("1st growth") Cell elongates and becomes "normal" size.
    B. S Phase- ("Synthesis" of DNA) DNA is replicated in this phase.
    C. G2 Phase- ("2nd growth") Organelles are "doubled."
    (Collectively these three phases are called Interphase)
    D. M Phase- ("Mitosis") When the cell undergoes division.
    E. C Phase- ("Cytokinesis") When the cell/s re-form membranes and other cytoskeletal structures. This starts in the M Phase. Cell divides completely here.

III. M-Phase
    A. Interphase (G1, S, G2)- DNA replicates here but this process is invisible, because the DNA is in the form of Chromatin- DNA is "uncondensed" and not wrapped around histames. The DNA is going from 46 pieces to 92 pieces of DNA.
    B. Prophase- DNA condenses around its histomes and forms Chromosomes (visible). In chromosomes, two identical pieces of DNA called Chromatids, are joined by a small bead called a Centromere. The Nuclear membrane breaks down and the Chromatid pieces spread randomly through the cell. 2 Centrioles break from the Centrosome and move to the poles of the cell.
    C. Metaphase- Chromatid pairs line up at the equator of the cell, and spindle fibers (made from microfiliments) develop from the centrioles and attach to them.
    D. Anaphase- Chromatin pairs separate and are pulled apart by the spindle and begin moving towards the poles.
    E. Telophase- Chromosomes reach the poles and Cytokinesis begins (the actual division of the cell)