1. Focus Questions:
Why do cells need to grow and divide?
How do cells divide?
What happens when cells divide incorrectly?

2. Reasons we need our cells to grow!
Growth of organisms
Repair of tissues

3. There are limits to a cell’s growth
A larger cell may experience “DNA overload”
As cells get larger they become less efficient at exchanging nutrients and materials such as oxygen, water, and food with its environment

4. DNA Overload
If a cell is large, there are more demands on its single copy of DNA
Think of a book in a library: the more people there are, the greater the likelihood that they will have to wait to read it

5. Exchanging Nutrients As a cell gets larger, what gets bigger?
Its volume!
Its surface area also gets larger, but not large enough!
Only so many materials are able to pass through the cell membrane at once
The surface area of many small cells is greater than one cell (or ever a few large cells)

6. Remember, cells must use diffusion and osmosis to obtain important nutrients, like oxygen and glucose

7. Cell Division - process by which a cell splits into two identical daughter cells
Occurs in two main phases: 
Interphase – cell copies its DNA and prepares for division
Mitosis – chromosomes separate into two new cells

8. Chromosomes DNA containing cell’s genetic code
During interphase, chromosomes are copied
- this produces two identical “sister chromatids”

11. The Cell Cycle

12. The Cell Cycle Interphase (longest phase)
G1 - first growth (gap) phase, new organelles produced
Synthesis - DNA makes a copy
G2 - second growth (gap) phase, preparing for mitosis
G0 - no growth phase, a cell may enter this phase
Mitosis - nucleus divides, ensuring each new cell has the exact number of chromosomes as parent

13. Life Cycle of the Cell Mitosis = nuclear division
Mitosis is followed by cytokinesis (cell division)
The steps of mitosis ensure that each new cell has the exact same number of chromosomes as the original

14. First, a little background info
Centrioles – produce spindle fibers during cell division
Spindle fiber – a tiny protein that helps chromatids separate during mitosis

15. Anatomy of a chromosome
Chromosome is composed of a pair of chromatids (sister chromatids)
Centromere is the center, where the two chromatids connect

16. Interphase • Prophase • Metaphase • Anaphase • Telophase
IPMAT

17. Interphase
Most of the time in the cell cycle is spent in interphase (95%)
Technically, it is not mitosis (Includes G1, S, G2)
Most cellular activity occurs in interphase
Reproduction of DNA and organelles

18. Prophase
Chromatin (stringy DNA) condenses into chromosomes (more compact DNA, which is more visible)

19. Prophase Centrioles migrate to opposite poles of the cell.
Spindle fibers form
Nuclear envelope (covering around nucleus) disappears.

20. Draw Prophase

21. Metaphase Nuclear envelope is gone Microtubules connect to chromosomes
Chromosomes aligned along middle of nucleus (on the equator)

22. Draw Metaphase

24. Anaphase
Chromosomes pulled apart by spindle

25. Draw Anaphase

26. Telophase Chromatids arrive on opposite sides of cell
Nuclear envelope begins to reform around each set of chromatids
Chromosomes unwind
Spindle fibers disperse

27. Draw Telophase

28. Cytokinesis
Cell membrane pinches off
New cell wall forms in plants

29. Interphase
Two new genetically identical cells
Cell Cycle continues

30. Mitosis: Can you name the stages?1 2 3 4 5

31. Mitosis: Can you name the stages?
Prophase 2 3 4 5

32. Mitosis: Can you name the stages?
Prophase
Metaphase 3 4 5

33. Mitosis: Can you name the stages?
Prophase
Metaphase
Anaphase 4 5

34. Mitosis: Can you name the stages?
Prophase
Metaphase
Anaphase
Telophase 5

35. Mitosis: Can you name the stages?
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

36. Important People Must Analyze Tasks Correctly
Phases of cell cycle - IPMATC
Important
People
Must
Analyze
Tasks
Correctly

37. Cell Cycle Images

38. 1. chromosomes visible (chromatids)
2. centrioles migrate to the poles
3. nuclear membrane disappears
4. nucleolus disappears
5. spindle forms

39. 1. chromosomes line up on the equator, spindle attaches

40. 1. chromatids separate and move to opposite poles

41. 1. chromosomes disappear • chromatin
2. nuclear membrane reforms
3. nucleoli reappears
4. spindle disappears
5. centrioles duplicate

42. - division of the cytoplasm to form 2 new daughter cells
- organelles are divided
- daughter cells are genetically identical
Cells return to interphase

44. Important People Must Analyze Tasks Correctly Impatient People May
Phases of cell cycle - IPMATC
Important
People
Must
Analyze
Tasks
Correctly
Impatient
People
May
Attack
Teachers
Constantly

50. Name the phases starting at the top.

51. Name the phase
Identify X
Identify Y

52. 5. Name the phase

53. 6. Name the phase