1. 10-2
Cell Division

2. Why do Cells divide?
Overload its DNA
Exchange of materials

3. The Cell Cycle
A series of events that a cell goes through as they grow and divide
Cell grows
Prepared to divide
This time in between divisions is called “Interphase”
Divides – forming two daughter cells
Each daughter cell repeats the cell cycle

4. Chromosomes
DNA is carried from one generation of cells to the next generation by chromosomes
Chromosomes are made up of DNA and proteins

5. Before Cell Division
Each chromosome is replicated (copied), this results in two identical “sister” Chromatids.

6. Mitosis tug-of-war
4 phases
Prophase,
metaphase,
anaphase,
telophase

7. Prophase Chromosomes become Visible Longest phase
The centrioles, separate and take positions on opposite sides of the nucleus
Centrioles acts as the anchors in the tug-of-war
Spindles begin to form, and attach to the chromosomes
Spindles are the ropes for the tug-of-war
Nuclear envelope (membrane) breaks down

9. Metaphase Chromosomes line up across the center of the cell
Shortest phase
Chromosomes line up across the center of the cell
tug-of-war is set and ready

11. Anaphase The centromeres begin to separate
The tug-of-war begins
The centromeres begin to separate
the Chromatids split, and become single chromosomes
The chromosomes continue to move until they are at opposite sides of the cell

13. Telophase The chromosomes begin to disperse and disappear
The nuclear envelope (membrane) reforms around each cluster of chromosomes
Spindles break apart and disappear
Tug-of-war is over = it’s a tie

15. Mitosis is over, but cell division is not
There is now one cell with two nuclei (nucleuses), each with a duplicate set of chromosomes
Cell must go through Cytokinesis

16. Cytokinesis The division of the cytoplasm
Usually occurs at the same time as telophase
In animal cells the cytoplasm pinches off
In plant cells a cell plate forms which eventually becomes a membrane.

17. The End Result Started with one cell
Ended with two cells, exactly the same as each other and exactly the same as the original cell.

19. End up with 2 identical cells
Starts with 1 cell 2n
End up with 2 identical cells 2n 2n