1. Cell Growth and Division

2. Why are cells so small? DNA Diffusion
Messages from the nucleus must be able to reach all parts of the cell
Diffusion
Nutrients must enter and wastes must leave
If the cell was too big, diffusion would happen too slowly

3. Why are cells so small? Surface Area vs. Volume
As a cell grows larger, the volume increases faster than the SA
A bigger cell needs more nutrients, but has relatively less SA to take in those nutrients

4. Surface Area vs. Volume Cell Size 5 cm 10 cm Surface Area (l×w×6)
Volume (l×w×h)
125 cm3
1000 cm3
SA to Volume Ratio
150/125 = 6:5
600/1000 = 6:10

5. Cell Cycle Cells divide before growing too large
Before dividing, cells must prepare
Preparation = Interphase
G1 phase: Cell grows larger
S phase: Cell makes new DNA for daughter cell
G2 phase: Cell makes new organelles for daughter cell

6. Cell Cycle

7. Chromosomes Each chromosome is replicated during the S phase
Centromere
Sister Chromatids
Each chromosome is replicated during the S phase
A replicated chromosome has two identical sister chromatids connected by a centromere

8. Mitosis
CLICK FOR MITOSIS VIDEO

9. Mitosis Four Stages: Prophase (pro- means first)
Metaphase (meta- means middle/after)
Anaphase (ana- means apart)
Telophase (telo- means far away/end)

10. Prophase Chromatin condenses into chromosomes
condensing
Chromatin condenses into chromosomes
Nuclear envelope and nucleolus disintegrate
Centrioles migrate to opposite ends of the cell
Spindle fibers form in foot ball shape across cell

11. Metaphase Chromosomes line up in the middle (equator) of the cell
Spindle fibers attach to centromeres

12. Metaphase

13. Anaphase Sister chromatids separate
Spindle fibers shorten, pulling chromatids to opposite ends of cell
Animal cells begin to pinch in
Plant cells begin to form cell plate in the middle

14. Anaphase

15. Telophase
Nuclear membrane built from ER around each set of chromosomes
Nucleolus reforms in each nucleus
Chromosomes become mass of chromatin

16. Two cells dividing into four
Telophase
Two cells dividing into four

17. Cytokinesis
Final division of cytoplasm resulting in two daughter cells
Animals – CM pinches together
Plants – Cell plate forms new CM dividing the daughter cells

18. Plant Cell Division
CLICK HERE FOR PLANT MITOSIS VIDEO

19. Which phases can you see?
Anaphase
Prophase
Metaphase
Telophase
Interphase

20. Knowing when to divide Cyclins
Protein that regulates the cell cycle in eukaryotes
Internal regulators – tell the cell when to enter mitosis
External regulators – control the rate of the cell cycle

21. Cellular Response to Injury

22. Effect of Cyclins Cytoplasm is injected into a second cell in G2 phase
Cytoplasm is removed from cell in mitosis
Second cell enters mitosis

23. Cancer
Cancer results when cells do not respond to cell cycle regulators
Cells grow unregulated, forming a tumor
Tumor damages surrounding tissue

24. Leukemia – Blood cancer

25. Mammary (Breast) Cancer

26. Skin Cancer