1. Section 2 Mitosis & Cytokinesis
Chapter 9
Section 2
Mitosis & Cytokinesis

2. Mitosis
consists of four stages

3. Prophase the stage that immediately follows G2
the chromatin condenses into CHROMOSOMES
at this point, each chromosome is attached to its replica at a structure called the CENTROMERE and is known as a SISTER CHROMATID

4. Prophase
the NUCLEAR ENVELOPE and the NUCLEOLUS seem to disappear

5. Prophase
a pair of microtubule structures called CENTRIOLES migrates to the poles (ends) of the cell – which have another type of microtubules called ASTER FIBERS coming out of them (only in animal and most protist cells)

6. Prophase
another type of microtubule structures called SPINDLE FIBERS form in the cytoplasm and attach to the SISTER CHROMATIDS on both sides of their centromere and then attach to opposite poles of the cell
this is the longest stage of mitosis

7. Metaphase the stage that immediately follows Prophase
the sister chromatids are pulled along the spindle fibers toward the CENTER/MIDDLE of the cell, and they line up on the EQUATOR of the cell
this is the shortest stage of mitosis

8. Anaphase the stage that immediately follows Metaphase
the spindle fibers shorten, which pulls at the centromere of each pair of SISTER CHROMATIDS, causing them to separate into two identical CHROMOSOMES

9. Anaphase
the spindle fibers then move the one of each identical chromosome toward opposite POLES of the cell

10. Telophase the stage that immediately follows Anaphase
the chromosomes at each pole of the cell decondense into CHROMATIN
two new NUCLEAR ENVELOPES form and the NUCLEOLI reappear

11. Telophase
the SPINDLE APPARATUS disassembles (some of the microtubules are used to build various parts of the CYTOSKELETON)
At this point, the nuclear material is divided, but the process of cell division in not yet complete
the cell has to go through CYTOKINESIS (the division of its cytoplasm)

12. Cytokinesis Animal Cells
uses microfilaments to constrict (pinch) the cytoplasm at an area called the FURROW and eventually splits the two cells apart

13. Cytokinesis Plant Cells
a CELL PLATE forms between the two daughter nuclei, then cell walls then form on either side of it