Notes Chapter 10 Cell Growth and Division

1. Notes Chapter 10 Cell Growth and Division

2. Why do cells divide rather than continuing to grow indefinitely?

3. Cell growth… - the larger a cell becomes, the more demands the cell places on its DNA and the more trouble it has movingenough nutrients and wastes across the membrane.

4. The volume and mass of a cell increases much more rapidly than the surfacearea…causing the ratio of surface area to volume (or mass) to decrease.

5. “Small town” getting larger… - not enough books in library (information – DNA) - has only a 2 lane main street (more traffic means slower movement)

6. CellCycle: cell growth and division – separating the cell contents into 2 equal parts Before a cell become too large… it divides, forming two daughter cells.

7. Cell Cycle

8. Before a cell divides… it must duplicate it’s genetic material…

9. chromosomes • Made of DNA(which carries the genetic code) and protein

10. Chromosomes are not visible except during cell division…otherwise the DNA and proteins are spread throughout the nucleus • At the beginning of cell division, chromosomes condense and are visible

12. chromatid • One of 2 identical “sister” parts of a duplicated chromosome

13. centromere • Area where the chromatids of a chromosome are attached

14. Quick Quiz • What is this called? • What is each individual “side” called? • What is the point of attachment called?

15. Student Activity You are going to make a Cell Cycle flip book. You’ll need 3 sheets of paper.

16. (We’re only using 3 sheets of paper… not 4.) Staple twice at the top… near the crease.

17. Flip Book Cont… • At the bottom edge of the top paper… write “Interphase”. You are going to draw a picture and take notes about interphase on this top page.

18. interphase • An “in-between” period of the cell cycle that separates each division of the cell

19. Interphase - the longest phase of the cell cycle Has three phases: G1 – cell growth S – DNA replication (and proteins) G2 – preparation for mitosis – shortest phase of interphase – many organelles and molecules needed for cell division are produced.

20. mitosis • Process of cell division... Dividing a cell’s nucleus.

21. Flip Book Cont… • At the bottom of the second page… write “Prophase”. • You are going to draw and take notes about Prophase on the second page.

22. prophase • Longest phase of mitosis (50% to 60% of time of mitosis) • Chromosomes become visible. • Centriolesseparate and take up positions on opposite poles (NOT in plants). • Spindle fibers (microtubules that help separate chromosomes) are formed. • Nucleolus disappears and the nuclear envelope breaks down. • http://www.cellsalive.com/mitosis.htm

23. Flip Book Cont… • At the bottom of the third page… write “Metaphase”.

24. metaphase • Chromosomes line up across the equator of the cell (middle). • Microtubules connect the centromere of each chromosome to the 2 poles of the spindle. • http://www.cellsalive.com/mitosis.htm

25. Flip Book Cont… • At the bottom of the fourth page write “Anaphase”.

26. anaphase • Centromeres that join the sister chromatids split. • Sister chromatids separate. • Chromosomes move until they separate into 2 groups near the poles. http://www.cellsalive.com/mitosis.htm

27. Flip Book Cont… • At the bottom of the fifth page write “Telophase”.

28. telophase • Chromosomes, that were condensed and distinct, begin to disperse (disappear). • Nuclear envelope re-forms around cluster of chromosomes. • Spindle breaks apart. http://www.cellsalive.com/mitosis.htm

29. Flip Book Cont… • At the bottom of the sixth page write “Cytokinesis”.

30. cytokinesis • Division of the cytoplasm Animal vs Plant

31. daughter cells

32. Cell Division Overview • http://www.cellsalive.com/mitosis.htm • http://www.johnkyrk.com/mitosis.html http://web.grcc.edu/biosci/pictdata/mitosis/planmito.htm

33. Cell Cycle Overview http://www.cellsalive.com/cell_cycle.htm

34. Mitosis Overview

35. Regulating cell division… cyclins – proteins that regulate the timing of the cell cycle (p. 250-251) • When an injury such as a cut in the skin occurs, cells at the edge of the cut will divide rapidly. • When the healing process nears completion, the rate of cell division slows down and then returns to normal.

36. Uncontrolled cell growth… cancer– a disorder in which some of the body cells lost the ability to control growth

37. Cancercells do notrespond to the signals that regulate the growth of most cells…

38. Cancer cells divide uncontrollably and form tumors. Cancer cells may break loose from tumors and spread throughout the body.