2. Why do cells need to divide ?

4. 1.Worn out cells need to be replaced. 2.Damaged cells need to be replaced. 3. Growth and development

5. What must cells do before they divide?

6. What can happen if cells aren’t divided correctly?

7. What happens if the mitochondria don’t divide correctly?

8. What happens if the lysosomes don’t divide correctly?

9. What happens if the nuclei don’t divide correctly?

10. Ok, so well what can happen to a cell if it doesn’t divide correctly?

11. Different Cells divide in different ways: Prokaryotic things (bacteria) do a very simple process to divide on cell into two cells called Binary Fission.

13. Eukaryotic things (like us) go through the cell cycle to divide.

14. There are three basic phases of a cell dividing into a new cell. A- Interphase- the cell grows, performs regular cell activities, and copies its DNA(most of the cell’s life is spent in this phase). B- Mitosis- (prophase, metaphase, anaphase, telophase)- the division of the nucleus and DNA C- Cytokinesis- splitting of the cytoplasm, resulting in two new daughter cells

15. In between each phase, there are Check Points to make sure that cells have done everything they need to do.

16. http://www.allthingsscience.com/video/490 /The-Stages-of-Mitosis

17. Cell division occurs in a series of stages or phases

19. Interphase

20. Chromosomes are copied (# doubles) Chromosomes appear as threadlike coils(chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at the end of the phase.

21. Centromere

22. Prophase Centrioles Spindle Fibers Chromosomes

23. Mitosis begins (cell begins to divide) Centrioles (or poles) appear and begin to move to opposite ends of the cell Spindle fibers form between the poles

24. Metaphase

25. Chromatids (or pairs of chromosomes) attach at the spindle fibers.

26. Anaphase

27. Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell.

28. Telophase

29. Two new nuclei form Chromosomes appear as chromatin (threads rather than rods) Mitosis ends

30. Cytokinesis

31. Cell membrane moves inward to create two daughter cells- each with its own nucleus with identical chromosomes.

32. http://www.youtube.com/watch?v=m73i1Zk8EA0&featu re=related

33. Close up…

34. Today’s lab: looking at onion mitosis

35. Close up…