1. Name 2 limitations to cell growth. How does DNA limit cell growth?
10.1 Pre-Read Questions
Name 2 limitations to cell growth.
How does DNA limit cell growth?
Why is the ratio of surface area to volume important?
Describe the process of cell division.

2. Ch 10: Cell Growth and Division

3. Does not continue to grow bigger
Cells
Does not continue to grow bigger
Cells just continue to produce more cells

4. Limits to Cell Growth
2 main reasons
Larger a cell becomes, the more demands the cell places on its DNA
Larger cells -- harder time processing information, harder time getting rid of wastes

5. Limits to Cell Growth
2 main reasons
2. Cell has more trouble moving enough nutrients and wastes in and out of cell

6. Reason #1 DNA “overload”
DNA = information that controls a cell’s function
if cells grow, DNA does not make extra copies
DNA would not be able to serve the needs of the cell
More people in a city, not enough police officers -- more crimes can occur without much control

7. Reason #2: Exchanging Materials
how fast materials leave or enter the cell depends on surface area
food and oxygen depend on cell volume

8. Ratio of Surface Area to Volume
as surface area increases, its volume increases at a faster rate

9. Ratio of Surface Area to Volume
Consequence = cells have a more difficult time to move needed materials in and waste products out

10. one cell divides into 2 new cells
Cell Division
how cells reproduce
one cell divides into 2 new cells
daughter cells

11. before cell division - cell copies DNA
Each daughter cell gets own copy of DNA

12. 10.2A
12 / 5 / 06

13. 2 Stages Mitosis = division of the cell nucleus
Cytokinesis = division of the cytoplasm

14. Mitosis
asexual
source of new cells

15. Chromosomes carries the genetic information consists of DNA
cells have specific number of chromosomes

16. Chromosome not visible until cell division
replicated before cell division
chromosomes change form to chromatids

17. Chromatids Separate from each other and go into daughter cells
attached at a centromere
located near the middle of the chromatids

18. Centromere
Chromatid

19. Cell Cycle
cell reproduction
forms two daughter cells
in between period = interphase

20. Cell Cycle: 4 phases consists of 4 phases
M phase = mitosis and cytokinesis
S phase = chromosome replication (S = synthesis)
G1 and G2 (G = gap) -- growth and activity

22. Interphase
3 of the 4 phases occur G1
S phase G2

23. G1 Phase
cell growing
increase in size and synthesize new proteins and organelles

24. S Phase
chromosome replication
proteins synthesized

25. G2 Phase
DNA replication complete at beginning
shortest phase

26. prepare for cell division
G2 Phase
organelles produced
prepare for cell division

27. 10.2 Post Read Questions
Describe the 2 stages of cell division.
Draw a chromosome and label and describe its parts.
What are the different phases of interphase? Describe each one.
What is the cell cycle?

28. 10.2 B
12 / 06 / 06

30. Interphase In between periods of cell division
Cell growth and DNA replication occur

31. Prophase first and longest phase (50%-60%) chromosome becomes visible
centrioles take position on opposite sides of nucleus at the centrosome

32. Prophase Centrioles lie in centrosome so they can organize the spindle
Spindle = fanlike microtubule structure that helps separate the chromosomes

33. Prophase
end = chromosomes coil and nuclear envelope break down

34. Metaphase lasts only a few minutes
chromosomes line up across the center of the cell

35. Metaphase (cont)
microtubules connect the centromere of each chromosome to the two poles of the spindle

36. Anaphase
centromeres that join the sister chromatids split into individual chromosomes and are moved apart to opposite poles

37. Telophase chromosomes become dense material spindle breaks apart
nucleolus appears

38. Cytokinesis Division of cytoplasm
usually occurs the same time as telophase
Animal Cell = cell membrane draw inward and pinched off
Plant cell = cell plate forms midway between the 2 nuclei; cell wall appears

39. I P M A T
NTERPHASE
ROPHASE
ETAPHASE
NAPHASE
ELOPHASE

40. Put the pictures in orderA B E
Put the pictures in order C D

41. C D E
ANSWER B A

42. Ch 10 Review Questions (Cont)
What is cytokinesis? When does it occur?
Compare how cytokinesis works between animal and plant cells.
Describe metaphase.
Describe anaphase.
If you were to look at a picture of telophase and anaphase, how can you distinguish the difference between the two?

43. 10.3
12 / 7 / 06

44. Review: Cell Cycle
Preparing for Cell Division
INTERPHASE G1 S G2

46. Review: Cell Cycle
Steps of Cell Division
Mitosis
Prophase
Metaphase
Anaphase
Telophase / Cytokinesis

47. Look at Figure 10.7
Observe what is going on
What is happening in each step?

48. regulates the timing of the cell cycle in eukaryotic cells
Cyclin
protein
regulates the timing of the cell cycle in eukaryotic cells

49. Regulatory Proteins
Two types
Internal Regulators
External Regulators

50. proteins that respond to events inside the cell
Internal Regulators
proteins that respond to events inside the cell
signals cell cycle to continue ONLY WHEN OTHER THINGS ARE COMPLETE
There are proteins that tell cells when ALL the chromosomes are complete and its ready to go onto the next step

51. External Regulator proteins that respond to events outside the cell
direct cells to speed up or slow down the cell cycle
example: growth regulators
Growth regulators control how a scab is form … tells it where to go and how much to put on

52. Uncontrolled Cell Growth
Cancer
body loses ability to control growth
does not respond to the regulator proteins
result = large masses of cells

53. Tumors masses of cells damages the surrounding tissues
cells break off and spread throughout the body

54. Cause of cancer brought on by smoking tobacco radiation exposure
viral infection
etc

55. 10.3 Review Questions
Why is it important for cells to have regulated cell growth?
What is the purpose of the protein cyclin?
Compare and contrast internal regulators and external regulators.
What is cancer? What causes cancer?