Cell division occurs in a series of stages, or phases. Mitosis Notes Cell division occurs in a series of stages, or phases.

1st: INTERPHASE Cell is in normal function, nucleus is visible Nuclear Membrane Nucleolus Cell is in normal function, nucleus is visible Nuclear membrane is intact Chromosomes are copied (# doubles) Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy (sister chromosome) change to sister chromatids at end of this phase Chromatin Cell Membrane

2nd: PROPHASE Mitosis begins (cell begins to divide) Centrioles Mitosis begins (cell begins to divide) Nuclear membrane dissolves Centrioles (or poles) appear and begin to move to opposite ends of cell Spindle fibers form between the poles Sister Chromatid Spindle Fibers Cell Membrane

3rd: METAPHASE Sister Chromatid Centromeres Spindle Fibers Asters Centrioles Cell membrane Chromatids (or pairs of chromosomes) attach to the spindle fibers Spindle fibers line chromatids up in the middle of the cell

4th: ANAPHASE Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell Centrioles Sister Chromatids Spindle Fibers Aster Cell Membrane

5th: TELOPHASE Two new nuclei form Chromosomes uncoil into chromatin Nucleus Cell Membrane pinches Nuclear Membrane Two new nuclei form Chromosomes uncoil into chromatin Cell membrane reforms and starts to pinch together Mitosis Ends

6th: CYTOKINESIS Nucleolus • Cell membrane moves inward to create two daughter cells - each with its own nucleus with identical chromosomes to the parent cell Chromatin Nuclear Membrane Cell Membrane