1. Ch. 10

2. Why are cells so small?????????

3. 1. DNA Overload – larger cells place more demands on the DNA. 2. Exchanging Materials – diffusion of materials takes time. ◦ As the ratio of surface area to volume gets small, the cell membrane has trouble diffusing materials fast enough.

4. Cell Size Surface Area (length x width x 6) Volume (length x width x height) Ratio of Surface Area to Volume Ratio of Surface Area to Volume in Cells

5.  As a cell grows, if it doesn’t do something about these two problems the cell will die…..  So before this occurs, the cell divides. ◦ This prevents DNA overload and increases surface area for diffusion of materials.

6. 10-2

7.  Asexual reproduction  Growth and development  Repair and maintenance

9.  Genetic information (DNA) within the nucleus of each cell..  The number of chromosomes is species specific. ◦ Hedgehog – 88 ◦ Chicken – 78 ◦ Horse – 64 ◦ Humans = 46 ◦ Rat – 42 ◦ Starfish – 38 ◦ Snail – 24 ◦ Koala - 16 ◦ Fruit flies = 8

10.  The genetic information must be copied before cell division. ◦ This process is called replication.  This insures each daughter cells gets a full set of genetic information. ◦ Without this the cell could not survive.

11.  The “life cycle” of a cell. Two main phases. ◦ Interphase = period of time between divisions; growth and preparation for division. Longest phase. ◦ M phase = cell division. Shortest phase. Two parts:  Mitosis (karyokinesis) – nuclear division  Cytokinesis – cytoplasmic division

12. M phase G 2 phase S phase G 1 phase The Cell Cycle Section 10-2

13. Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Mitosis and Cytokinesis

14. Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Mitosis and Cytokinesis

15. Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Mitosis and Cytokinesis

16. Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Mitosis and Cytokinesis

17. Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Mitosis and Cytokinesis

18. Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Mitosis and Cytokinesis

19.  The cell membrane pinches in.

20.  A cell plate forms.

21. Onion Root Tip

22. http://www.youtube.com/watch?feature=playe r_embedded&v=VGV3fv-uZYI http://www.youtube.com/watch?v=aDAw2Zg4I gE&feature=player_embedded http://www.youtube.com/watch?v=pOsAbTi9t Hw&feature=player_embedded

23.  Mitosis produces two genetically identical cells. ◦ THEY HAVE THE SAME # AND TYPE OF CHROMOSOMES. ◦ THEY HAVE THE SAME GENETIC INFORMATION (GENES). ◦ THERE IS NO GENETIC VARIATION. THEY ARE CLONES.

24.  http://nobelprize.org/educational_games/me dicine/2001/cellcycle.html http://nobelprize.org/educational_games/me dicine/2001/cellcycle.html

25. 10-3

26.  Not all cells have the same length cell cycle… ◦ Nerve and muscle cells – very long; rarely divide ◦ Skin and blood cells – short; often divide

27. What controls the length of the cell cycle??????

28.  Contact inhibition – ◦ When cells come in contact with each other, they usually stop growing. ◦ Cells at the site of an injury lose contact inhibition and begin growing.  This repairs the injury.

29. Control of Cell Division Section 10-3

30.  Cyclins – proteins that regulate the timing of the cell cycle in eukaryotic cells. ◦ Internal regulators – proteins that allow the cell cycle to proceed in response to events going on in the cell. ◦ External regulators – proteins that speed up or slow down the cell cycle in response to events outside the cell.

31. A sample of cytoplasm is removed from a cell in mitosis. The sample is injected into a second cell in G 2 of interphase. As a result, the second cell enters mitosis. Effect of Cyclins Section 10-3

32.  Cancer – a disorder in which cells do not respond to normal regulatory signals. ◦ Cancer cells have no contact inhibition. ◦ Cancer cells divide uncontrollably and produce masses called tumors.  Benign tumors no longer are growing.  Malignant tumors are currently growing and may spread.  Cancer therapy involves chemotherapy, radiation treatments and surgical removal.

33.  Carcinogens – agents that cause the development of carcinomas (tumors). ◦ Radiation – x-rays, uv rays ◦ Chemicals – cigarette smoke, asbestos ◦ Genetics  Cancer therapy involves chemotherapy, radiation treatments and surgical removal.