1. Cell Division and Mitosis One parent cell giving rise to two identical daughter cells

2. What is Mitosis? Mitosis is the process of duplication of chromosomes and division of the nucleus prior to cell division.

3. 5 Phases of Mitosis Interphase Prophase Metaphase Anaphase Telophase

4. Interphase Includes the time that the cell is not actively dividing so may last a long time The cell carries out its normal life functions during this phase DNA is in the form of chromatin – long threadlike strands, not visible with light microscope

5. Late Interphase Chromosomes have replicated. Nuclear membrane is still intact Nuclei stained blue; Center and right cell in interphase Public Domain: http://en.wikipedia.org/wiki/File:HeLa_cells_stained_wit h_Hoechst_33258.jpg http://en.wikipedia.org/wiki/File:HeLa_cells_stained_wit h_Hoechst_33258.jpg http://en.wikipedia.org/wiki/File:HeLa_cells_stained_wit h_Hoechst_33258.jpg

6. Interphase = Chromatin

7. Prophase Chromatin coils into chromatids and become easily visible with light microscope. Duplicate chromosomes are attached at the centromeres. Fluorescence microscope image of two mouse cell nuclei in prophase (scale bar is 5 µm). http://en.wikipedia.org/wiki/Prophase

8. Prophase In the cell: Centrioles move to opposite ends of the cell (animal cells) Spindle forms Nucleolus disappears Nuclear membrane breaks down

9. Different Forms of Chromosomes (1) Chromatin during interphase with centromere. (2) Condensed chromatin during prophase. (Two copies of the DNA molecule are now present) (3) Sister chromatids from the end of prophase through anaphase. Image modified from http://commons.wikimedia.org/wiki/File:Chromatin_chromosome.png http://commons.wikimedia.org/wiki/File:Chromatin_chromosome.png

10. Prophase http://en.wikipedia.org/wiki/Prophase Chromosomal components: (1) Chromatid (2) Centromere (3) Short arm (4) Long arm http://en.wikipedia.org/wiki/Centromere

11. Metaphase The chromosomes have aligned along the equator of the cell attached to the spindle fibers by the centromeres Some rights reservedSome rights reserved by Carolina Biological Supply CompanyCarolina Biological Supply Company

12. Metaphase http://en.wikipedia.org/wiki/Metaphase

13. Anaphase Each centromere splits allowing identical sister chromatids to separate and move along the spindle fibers toward opposite ends of the cell.

14. Anaphase Early Anaphase: The chromosomes are starting to migrate toward opposite poles. Late Anaphase: The contraction of the spindle fibers has moved the separate masses of chromatids farther from the equator. Some rights reservedSome rights reserved by Carolina Biological Supply CompanyCarolina Biological Supply Company Onion Root Tip Whitefish egg

15. Anaphase http://en.wikipedia.org/wiki/Anaphase

16. Telophase The chromatids have reached the poles. The chromatids uncoil back into chromatin. Each set of chromosomes becomes incorporated in a new nucleus as the nuclear membrane reforms. Cytokinesis or cell division now occurs. http://en.wikipedia.org/wiki/Telophase

17. Daughter Cells in Interphase After cytokinesis: Cells may enter a prolonged period of interphase when all the processes that normally take place in the cell occur, except for cell division. Cells may repeat the steps of mitosis and divide again

18. Phases of Mitosis – Another Look Public Domain: http://commons.wikimedia.org/wiki/File:Interphase_and_Mitosis.svg http://commons.wikimedia.org/wiki/File:Interphase_and_Mitosis.svg

19. Mitosis in Onion Root Tip http://commons.wikimedia. org/wiki/File:Onion_root_mi tosis.jpg http://commons.wikimedia. org/wiki/File:Onion_root_mi tosis.jpg Can you find: ProphaseMetaphaseAnaphaseTelophase

20. http://commons.wikimedia.org/wiki/File:Mitosis_schematic_diagram-en.svg