1. MITOSIS

2. Why does a cell need to duplicate?
Purpose: to replenish dead or dying cells, to allow an organism to grow and develop

3. 3 stages of the cell cycle:
Interphase – cell grows and carries out its normal functions, replication of chromosomes
Mitosis – genetic material in the nucleus is divided equally into two new nuclei
Cytokinesis – rest of the cell divides
-each ‘daughter’ cell is identical to the parent cell

4. Cell Cycle Animation: http://www.cellsalive.com/cell_cycle.htm
The Cell Cycle
Interphase:
in between stages of dividing
G1—beginning cell growth
S—DNA duplicates (makes a copy)
DNA is in the form of chromatin
G2—cell undergoes its function
DNA is replicated along with organelles and other cellular components and the cell prepares for division.
Mitosis:
division of the cell
Cell Cycle Animation:

5. Mitosis Mitosis animations:
(1:22 min)
(1:30 min)
Beginning of second class

6. Important information
DNA is found in the nucleus. It is important that the doubles before it divides into 2 cells.
The form of DNA will change throughout the cell cycle.
Form of DNA
Stage of the cell cycle
Structure
Chromatin
Interphase- G1,S,G2
Chromosomes
Mitosis
Sister chromatid
Mitosis- Prophase, metaphase

7. Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Interphase
Animal cell
Plant cell
Photographs from:

8. 1st step in Mitosis: Prophase (preparation phase)
DNA recoils and the chromosomes condense and become shorter and thicker
the nuclear membrane dissolves and disappears
the spindle fibres (which attach to chromosomes during cell division) begin to form

9. Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis Prophase
Animal cell
Plant cell
NOTE: In animal cells, centrioles are involved in the formation and organization of spindle fibres.
Photographs from:

10. 2nd step in Mitosis: Metaphase (organizational phase)
chromosomes line up in the middle of the cell with the help of spindle fibers attached to the centromere of each replicated chromosome (sister chromatids)

11. Mitosis Metaphase Animal cell Plant cell
Photographs from:

12. 3rd step in Mitosis: Anaphase (separation phase)
chromosomes split in the middle (centromeres divide) and the sister chromatids are pulled by the spindle fibres to opposite poles of the cell

13. Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis Anaphase
Animal cell
Plant cell
Photographs from:

14. 4th step in Mitosis: Telophase
chromosomes reach opposite poles of the cell and begin to unwind
spindle fibres dissolve and nuclear membrane forms around the chromosomes

15. Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis Telophase
Animal cell
Plant cell
Photographs from:

16. After Mitosis: Cytokinesis
The actual splitting of the cytoplasm and all the organelles into two separate cells called daughter cells.
Occurs differently in both plant and animal cells.
Beginning of cytokinesis in a plant:
Beginning of cytokinesis in an animal: