1. Cell Growth

2. Learning Objectives
Explain how cell division solves the problem of cell growth

3. Calculating Surface AreaB A
Surface Area = Area X # of sides
Area = A X B

4. Calculating Volume
Volume = Length X Height X Width

5. Surface Area to Volume
Surface area - 6mm2
Volume - 1mm3
Surface area - 24mm2
Volume - 8mm3
Surface area - 96mm2
Volume - 64mm3
As the cell grows larger, the cell’s volume increases faster than the surface area, causing problems for the cell.

6. Limits to Cell Growth
Larger cells have more trouble moving nutrients and wastes across the membrane
DNA overload - large cells cannot make enough DNA to meet it’s needs

7. When animals grow larger, do their cells increase in size or do they produce more cells?

8. Cell Division
Before a cell becomes too large, it divides forming two “daughter” cells - Cell Division

9. Stop Here

10. Cell Division

11. Learning Objectives
Explain the main events of the cell cycle

12. The Cell Cycle
During the cell cycle, a cell grows, prepares for cell division (interphase) and divides to form two daughter cells (M phase).

13. 2 Stages of the Cell Cycle
Stage 1 = Interphase
Stage 2 = Mitotic phase

14. Interphase 90% of a cell’s time may be spent in interphase.
Three parts: G1, S and G2 phases
G1 phase - Cells grow and replicate organelles.
S phase - DNA synthesis occurs and chromosomes are replicated.
G2 phase - additional growth and preparation for mitosis.
90% of a cell’s time may be spent in interphase.

15. Mitotic phase (M phase)
Two main stages: Mitosis and cytokinesis
Mitosis - division of the cell nucleus
Cytokinesis - division of the cytoplasm

16. Purpose of The Cell Cycle
The purpose of the cell cycle is to regulate cell division, which replicates each parent cell to form two identical daughter cells.

17. Stop Here

18. Phases of Mitosis

19. Learning Objectives
Describe what happens during the four phases of mitosis

20. Mitosis Mitosis - division of the cell nucleus
Mitosis is divided into four phases:
Prophase
Metaphase
Anaphase
Telophase

21. Interphase Cell grows and replicates its DNA and centrioles.
Nucleolus
Centrioles
Chromatin
Nuclear Envelope
Cell grows and replicates its DNA and centrioles.
Prepares for mitosis.

22. Prophase Chromatin condenses into chromosomes.
Spindles
Centrioles
Nuclear Envelope
Chromatin condenses into chromosomes.
Centrioles separate and spindles begin to form.
Nuclear envelope breaks down.

23. Metaphase Chromosomes line up across the center of the cell.
Centromere
Spindles
Chromosomes line up across the center of the cell.
Each chromosome is connected to the spindle fiber at its centromere.

24. Anaphase
Sister Chromatids
Paired chromosomes (sister chromatids) separate into individual chromosomes.
Chromosomes move to opposite ends of the cell.

25. Telophase Two nuclear envelopes form around chromosomes
Chromatin
Nuclear Envelope
Two nuclear envelopes form around chromosomes
Chromosomes uncoil into chromatin.

26. Cytokinesis
Cytokinesis - division of the cytoplasm. Two daughter cells with an identical set of chromosomes are formed.

27. YouTube Video
Mitosis

28. Stop Here

29. Regulation of the Cell Cycle

30. Learning Objectives Describe how the cell cycle is regulated
Explain how cancer cells are different from normal cells

31. Functions of Cell Division
Reproduction - formation of an organism, increasing the population.
Growth - development of multicellular organisms.
Repair - repair and renew cells that die (apoptosis) from normal wear or damage.

32. Regulating the Cell Cycle
Not all cells move through the cell cycle at the same rate.
Cells of the skin and digestive tract divide rapidly.
Adult muscle and nerve cells do not divide.

33. How is the cell cycle regulated?
Internal Regulators:
Proteins that respond to events inside the cell. Ex. Cyclin
External Regulators:
Proteins that respond to events outside the cell. Ex. Growth Factors

34. Uncontrolled Cell Growth
Cancer - a disorder in which some of the body’s own cells lose the ability to control growth.

35. Cancer Divide uncontrollably Form masses called tumors
Damage surrounding tissue
Break loose from tumors and spread throughout the body - Metastasis

36. Cancer Facts and Figures
Cancer is a leading cause of death worldwide.
Deaths caused by cancer this year: 7,602,215

37. Stem Cells
Stem cells - unspecialized cells that have the potential to become a variety of cell types.
Every cell in an organism was produced by mitosis from stem cells.

38. Cancer: Unregulated Cell Division
YouTube Video
Cancer: Unregulated Cell Division

39. Stop Here