Mitosis

Mitosis

1. The process by which one cell separates it's genetic info into two identical cells.

2. Interphase

   • G1 phase: growth of cell and organelles.
   • S phase: synthesis, DNA is replicated
   • G2 phase: further preparation for division.

3. Prophase

   • Chromatin coils to form chromosomes.
   • Nucleolus disappears. Still has nuclear envelope.
   • Centrosomes split and move to opposite sides of the nucleus.
   • Spindle fibers connect centrosomes.
     • Spindle fibers are microtubules, and the centrosome is a microtubule organizing center. (MTOC)
     • Asters: short arrays of microtubules extended away from the spindle.

4. Metaphase

   • Chromosomes line up with with centromeres in a plane in the center of the spindle apparatus. (metaphase plate)
   • Chromosomes still consist of 2 sister chromatids that straddle the metaphase plate.

5. Anaphase

   • Sister chromatids separate.
   • Kinetochore fibers shorten and pull sister chromatids to each pole.
   • Non-kinetochore fibers elongate, pushing the poles apart.
   • Sister chromatids now called chromosomes. Each chromosome= 1 chromatid.
   • At the end of anaphase, the 2 poles have equivalent and complete sets of chromosomes.

6. Telophase

   • 2 daughter nuclei reform.
   • Spindle begins to dissemble, nuclear envelope and nucleoli reform.
   • Chromatin fiber of each chromosome becomes less likely coiled.
   • 2 genetically identical daughter nuclei are seen.

7. Cytokinesis

   • Subdivision of the cytoplasm.
   • Animals and Protozoans: a furrow forms, pinching the cytoplasm. Actin filaments and Myosin.
   • Plants, Fungi, and Algae: vesicles containing cell wall material fuse along the midline, and a continuous cell wall is formed.

8. Prometaphase

   • Chromosome condensation is complete. Each chromosome= 2 chromatids.
   • Nuclear envelope breaks down.
   • Microtubules of the spindle now invade the nucleus and interact with the centrosomes.
     • Kinetochore fibers attach to chromosomes at the kinetochore
     • Non-kinetochore microtubules run from centrosome to centrosome.