Interest Grabber

1. Interest Grabber Section 10-1 • Getting Through • Materials move through cells by diffusion. Oxygen and food move into cells, while waste products move out of cells. How does the size of a cell affect how efficiently materials get to all parts of a cell? • Work with a partner to complete this activity. 1. On a sheet of paper, make a drawing of a cell that has the following dimensions: 5 cm x 5 cm x 5 cm. Your partner should draw another cell about one half the size of your cell on a separate sheet of paper. 2. Compare your drawings. How much longer do you think it would taketo get from the cell membrane to the center of the big cell than from the cell membrane to the center of the smaller cell? 3. What is the advantage of cells being small?

2. Section Outline Section 10-1 • 10–1 Cell Growth A. Limits to Cell Growth 1. DNA “Overload” 2. Exchanging Materials 3. Ratio of Surface Area to Volume • Cell Division SURFACE AREA TO VOLUME RATIO LAB

3. 10-1 Cell Growth Limits to Cell Growth • 2 Reasons why cells divide rather than continue to grow indefinitely: • The larger a cell becomes, the more demands the cell places on its DNA • The cell has more trouble moving enough nutrients and wastes across the cell membrane

4. 10-1 Cell Growth Limits to Cell Growth • DNA store information that controls a cell’s function. • DNA is found in the nucleus of the cell. • Food, oxygen, and water must enter a cell through the cell membrane • Waste must exit a cell through the cell membrane.

5. 10-1 Cell Growth Limits to Cell Growth • The rate at which things can enter or exit the cell is dependent on a cell’s surface area. • Surface area is the total area of the cell membrane. • The rate at which food and oxygen are used up and waste is produced is dependent on the cell’s volume. • The surface area : volume ratio limits cell growth

6. Ratio of Surface Area to Volume in Cells Section 10-1 Cell Size Surface Area (length x width x 6) Volume (length x width x height) Ratio of Surface Area to Volume

7. 10-1 Cell Growth Limits to Cell Growth • Volume increases more rapidly than the surface area. This causes a decrease in the surface area to volume ratio

8. 10-1 Cell Growth Division of the Cell • Cell division is the process by which a cell divides into two new daughter cells. • Before a cell divides, the cell replicates its DNA. This ensures that each daughter cell will receive a full copy of the DNA.

9. Interest Grabber Section 10-2 • Cell Cycle • The cell cycle represents recurring events that take place in the period of time from the beginning of one cell division to the beginning of the next. In addition to cell division, the cell cycle includes periods when the cell is growing and actively producing materials it needs for the next division. 1. Why is the cell cycle called a cycle? 2. Why do you think that it is important for a cell to grow in size during its cell cycle? 3. What might happen to a cell if all events leading up to cell division took place as they should, but the cell did not divide?

10. Section Outline Section 10-2 • 10–2 Cell Division A. Chromosomes B. The Cell Cycle C. Events of the Cell Cycle D. Mitosis 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase E. Cytokinesis

11. 10-2 Cell Division • 2 Stages of cell division in eukaryotes: • Mitosis • Cytokinesis • Mitosis is the division of the nucleus. • Cytokinesis is the division of the cytoplasm.

12. 10-2 Cell Division Chromosomes • Chromosomes contain the genetic information that is passed on from one generation of cells to the next. • Chromosomes are made up of DNA and proteins. • Human cells have 46 chromosomes. • Chromosomes are only visible during cell division.

13. 10-2 Cell Division Chromosomes • Before cell division, each chromosomes replicates, creating 2 identical sister chromatids. • Each pair of chromatids is attached at an area called the centromere which is usually located in the center. • When a cell divides, the sister chromatids separate and each new cell receives one of the sister chromatids.

14. 10-2 Cell Division Chromosomes

15. 10-2 Cell Division The Cell Cycle • The cell cycle is the series of events that cells go through as they grow and divide. • During the cell cycle a cell grows, prepares for division, and divides into two daughter cells, each of which then begins the cycle again.

16. 10-2 Cell Division The Cell Cycle • The 4 phases of the cell cycle: • G1 Phase- Cell Growth • S Phase – DNA replication • G2 Phase- Preparation for Mitosis • M Phase- Mitosis and Cytokinesis • Traditionally, the G1, S and G2 Phases are called interphase.

17. Figure 10–4 The Cell Cycle Section 10-2 G1 phase M phase S phase G2 phase

18. 10-2 Cell Division Events in the cell cycle • G1 Phase • Cell increases in size. • Synthesis of new proteins and organelles.

19. 10-2 Cell Division Events in the cell cycle • S Phase • Synthesis of DNA • Chromosomes are replicated • Key proteins associated with chromosomes are synthesized.

20. 10-2 Cell Division Events in the cell cycle • G2 Phase • 1. Organelles and molecules needed for cell division are produced.

21. Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Centromere Chromatin Centriole Nuclear envelope Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Individual chromosomes Telophase Anaphase Nuclear envelope reforming

22. 10-2 Cell Division Mitosis • 4 Stages of mitosis: • Prophase • Metaphase • Anaphase • Telophase

23. 10-2 Cell Division Mitosis • Prophase • Chromatin condenses into chromosomes • Centrioles separate to the poles • Spindle forms from microtubules • Nucleolus disappears • Nuclear envelope disappears

24. Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Centromere Chromatin Centriole Nuclear envelope Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Individual chromosomes Telophase Anaphase Nuclear envelope reforming

25. 10-2 Cell Division Mitosis • Metaphase • Chromosomes line up across the center of the cell • Each chromosome attaches to the spindle at the centromere

26. Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Centromere Chromatin Centriole Nuclear envelope Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Individual chromosomes Telophase Anaphase Nuclear envelope reforming

27. 10-2 Cell Division Mitosis • Anaphase • Centromeres split allowing each sister chromatid to become a single stranded chromosome. • Chromosomes move toward each pole

28. Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Centromere Chromatin Centriole Nuclear envelope Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Individual chromosomes Telophase Anaphase Nuclear envelope reforming

29. 10-2 Cell Division Mitosis • Telophase • Chromosomes uncoil. • Spindle breaks down • Nuclear envelope reforms • Nucleolus reforms

30. Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Centromere Chromatin Centriole Nuclear envelope Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Individual chromosomes Telophase Anaphase Nuclear envelope reforming

31. 10-2 Cell Division Cytokinesis • Cytokinesis is the division of the cytoplasm • Cytokinesis usually occurs at the same time as telophase. • In animal cells, the cell membrane draws inward until the cytoplasm is pinched into two equal parts. • In plant cells, a cell plate forms half way between the 2 nuclei and gradually develops into a cell membrane and cell wall.

32. Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Centromere Chromatin Centriole Nuclear envelope Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Individual chromosomes Telophase Anaphase Nuclear envelope reforming

33. M phase (Mitosis) Interphase G1 phase S phase G2 phase Prophase Metaphase Anaphase Telophase Concept Map Section 10-2 Cell Cycle includes is divided into is divided into

34. Interest Grabber Section 10-3 • Knowing When to Stop • Suppose you had a paper cut on your finger. Although the cut may have bled and stung a little, after a few days, it will have disappeared, and your finger would be as good as new. 1. How do you think the body repairs an injury, such as a cut on a finger? 2. How long do you think this repair process continues? 3. What do you think causes the cells to stop the repair process?

35. Section Outline Section 10-3 • 10–3 Regulating the Cell Cycle A. Controls on Cell Division B. Cell Cycle Regulators 1. Internal Regulators 2. External Regulators C. Uncontrolled Cell Growth

36. 10-3 Regulating the cell cycle Controls of Cell Division • When placed in a petri dish, cells will divide until they run out of room. • If more space is created, the cells will resume cell division. • This shows that cell growth and division can be turned on and off

37. Control of Cell Division Section 10-3

38. 10-3 Regulating the cell cycle Controls of Cell Division • An example of this is when we cut our skin or break a bone. • Some cell like digestive tract cells and bone marrow cells reproduce quickly, while other cells like neurons and cardiac muscle cells cannot divide.

39. 10-3 Regulating the cell cycle Cell Cycle Regulators • Cyclins are proteins that regulate the timing of the cell cycle in eukaryotic cells. • 2 types of regulatory proteins: • Internal regulators: proteins that respond to events inside the cell (ex: mitosis only happens if chromosomes have replicated, anaphase, doesn’t happen if chromosomes aren’t attached to spindle) • External Regulators: proteins that respond to events outside the cell (ex: growth factors important during embryonic development or wound healing)

40. Figure 10–8 Effect of Cyclins Section 10-3 The sample is injected into a second cell in G2 of interphase. A sample of cytoplasm is removed from a cell in mitosis. As a result, the second cell enters mitosis.

41. 10-3 Regulating the cell cycle Uncontrolled Cell Growth • Cancer is a disorder in which some of the body’s own cells lose the ability to control growth. • Cancer cells do not respond to the signals that regulate the growth of most cells. • Cancers have many causes such as smoking tobacco, radiation exposure, viral infection or defective genes.

42. Video Contents Videos • Click a hyperlink to choose a video. • Animal Cell Mitosis • Animal Cell Cytokinesis

43. Video 1 Video 1 • Click the image to play the video segment. Animal Cell Mitosis

44. Video 2 Video 2 Animal Cell Cytokinesis • Click the image to play the video segment.

45. Internet Go Online • Links on cell growth • Links from the authors on stem cells • Share cell cycle lab data • Interactive test • For links on cell division, go to www.SciLinks.org and enter the Web Code as follows: cbn-3102. • For links on the cell cycle, go to www.SciLinks.org and enter the Web Code as follows: cbn-3103.

46. Section 1 Answers Interest Grabber Answers 1. On a sheet of paper, make a drawing of a cell that has the following dimensions: 5 cm x 5 cm x 5 cm. Your partner should draw another cell about one half the size of your cell on a separate sheet of paper. 2. Compare your drawings. How much longer do you think it would taketo get from the cell membrane to the center of the big cell than from the cell membrane to the center of the smaller cell? It would take twice the amount of time. 3. What is the advantage of cells being small? If cells are small, materials can be distributed to all parts of the cell quickly.

47. Section 2 Answers Interest Grabber Answers 1. Why is the cell cycle called a cycle? It represents recurring events. 2. Why do you think that it is important for a cell to grow in size during its cell cycle? If a cell did not grow in size, each cell division would produce progressively smaller cells. 3. What might happen to a cell if all events leading up to cell division took place as they should, but the cell did not divide? Students may infer that a cell that undergoes all sequences of the cell cycle would grow increasingly larger—to a point at which the cell could no longer exchange materials with the environment efficiently enough to live.

48. Section 3 Answers Interest Grabber Answers 1. How do you think the body repairs an injury, such as a cut on a finger? The cut is repaired by the production of new cells through cell division. 2. How long do you think this repair process continues? Cell division continues until the cut is repaired. 3. What do you think causes the cells to stop the repair process? Students will likely say that when the cut is filled in, there is no room for more cells to grow.

49. End of Custom Shows • This slide is intentionally blank.