1. Growth and Development!!
10-1 Cell Growth
Growth and Development!!

2. When Do New Cells Need to Form?
A. Growth - More cells
B. Maintenance (repair and replacement)--> intestinal lining/RBC’s)
C. Asexual reproduction
D. Formation of sex cells (Meiosis)

3. Limit of cell size?
1. TOO SMALL - There will not be enough room for all the organelles to carry out the processes needed.

4. 2. TOO BIG!: Cell membrane cannot control all movements of materials
The larger a cell grows the more trouble it has…
moving enough nutrients in
Moving all the waste materials out

5. Problem with Being Too Big!!
The volume gets too big for the surface area.
The cell membrane cannot control all the movement in and out when the volume is too large.
Your cells cannot too large either. The surface area must be in the correct ratio of the volume.
Neurons are very long and skinny so that ration is correct.

6. S.A. = 4 (pi) r 2 Radius 1cm S.A. = _____ V = ______ Ratio SA:V = ___
S.A. = __13cm2___
V = __4cm3____
Ratio SA:V = _13:4 or 3.25:1__
Radius 2cm
S.A. = ___50cm2__
V = __33cm3____
Ratio SA:V = 50:33_or 1.51:1
Radius 3cm
S.A. = __113cm2_
V = ___113cm3___
Ratio SA:V = _113:113 or 1:1__
Radius 3cm
S.A. = _____
V = ______
Ratio SA:V = ___
S.A. = 4 (pi) r 2
As the spheres get larger what happens to the SA:V ratio?

7. 3rd problem: DNA overload

8. 3rd Problem - Too Big 3. DNA overload
Your DNA controls all activities in the cell. When the cell gets too big then the DNA cannot control all activites.

9. Cells Divide at Different Rates
The rate of cell division is determined by the body’s need for that type of cell.
Nerve cells do not divide because they do not die like our skin cells.
A new layer of skin is replaced every 3 weeks. The lining of your intestines has to be replaced often because of the wear and tear. This is also skin cells.

10. The Cell Cycle and Mitosis

11. Cell Cycle – life of a cell
The life of a cell. It has a pattern of cell growth, DNA replication, and cell division. Results in two new daughter cells.

12. The Cell Cycle
The sequence of growth and division of a cell.
95% of cell cycle in interphase(growth)
5% of cell cycle in mitosis(division)

13. 3 Main Events of a Cell Cycle
1. Interphase
G1 - growth
S – DNA replication
G2 – growth and prepare for division
2. Mitosis Phase – nucleus dividing
Prophase
Metaphase
Anaphase
Telophase
3. Cytokinesis – cell division

14. What’s
Missing?

15. M Phase, Cell Division and Mitosis

16. Cell Cycle http://www.cellsalive.com/mitosis.htm

17. The Cell Cycle - series of events that cells go through as they grow and divide
The cell cycle is divided into two halfs
Interphase - period of the cell cycle between cell divisions
Mitosis phase and cytokinesis – period of time when mitosis and cell division occurs

18. Definitions Histones Telomeres Somatic cells Chromatin Chromosomes
Centromeres
Spindle fibers

19. Some Definitions
Histones: proteins that DNA will wrap around. This helps the DNA to fit.
Telomeres: End of DNA molecules to prevent them from attaching to each other. They do not contain genes.
Somatic Cells – body cells
Produced through mitosis
Has 46 chromosomes (23 pairs)

20. Chromatin - A complex of DNA and proteins in the cell nucleus that condenses to form chromosomes during cell division(loose DNA).
Chromosomes – Condensed Chromatin(X)
They are the same stuff, just in different forms
Centromeres: Center point where chromatids are attached.
Spindle Fibers - Fibers that pull part the chromosomes during mitosis.

21. Chromatin condenses in chomosomes before mitosis begins
Chromosomes

22. Parts of Interphase G1 Phase(growth) Cell grows
Synthesize new proteins and organelles
Doing their jobs
Longest phase of cell cycle

23. S Phase S Phase(synthesis) Chromosomes(DNA) are replicated
Key proteins associated with replication are made (centromeres

24. Gap 2 Phase G2 Phase(growth) Shortest of the 3 phases of interphase
Organelles and molecules for cell division are produced (centrioles)
Check-up phase before mitosis

25. G - 0 Stage
This is a stage of interphase that SOME cells enter. Cells such as nerve and white blood do not divide often so they enter this stage of rest.

26. Animated Cycle

28. What stops cell from growing?
Proximity to neighbor cells.
Cells in a petri dish will continue to grow until they come into contact with other cells.
Similarily, skin around a wound
After a cell has quit growing, it is time to divide!!!
Mitosis

29. MITOSIS

30. Mitosis
Division of the nucleus.
Followed by cytokinesis!!!
The daughter cells are identical to one another and to the original parent cell.

31. Mitosis
Prophase
Metaphase
Anaphase
Telophase

32. Prophase Longest phase of mitosis Chromatin condenses into chromosomes
Spindle fibers form and attach to centrioles
Nuclear membrane dissappears
Nucleolus breaks down

34. Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Prophase
Plant Cell
Animal Cell
Photographs from:

35. Prophase The cell prepares for nuclear division
Animal Cell
Packages DNA into chromosomes
Plant cell
Packages DNA into chromosomes

36. Metaphase Centromeres line up across the center of the cell
Spindle fibers connect to centromeres

38. Anaphase
Chromosomes
are pulled apart by spindle into individual chromatids.
The chromatids
are now considered
Chromosomes!!

39. Anaphase Centromeres split
Sister chromatids are pulled apart to opposite poles of the cell
Each chromatid is now a separate chromosome

42. Telophase Nuclear envelopes (2) and nucleolus reform
Chromosomes begin to uncoil
Spindle fibers disappear.

43. Mitosis Animation

44. Animal Mitosis -- Review
Interphase                                                             
Prophase                                                             
Metaphase                                                             
Anaphase                                                             
Telophase                                                             

45. Plant Mitosis -- Review
Interphase                                                             
Prophase                                                             
Metaphase                                                             
Anaphase                                                             
Telophase                                                             

46. Cytokinesis
Cytoplasm divides
Two new daughter cells are now separate

47. Cytokinesis The cytoplasm pinches in half Animal - cleavage furrow
Cytokinesis
The cytoplasm pinches in half
Animal - cleavage furrow
Plants - cell plate

48. In plant cells, a cell plate forms
In plant cells, a cell plate forms. The cell plate is synthesized by the fusion of multiple membrane-bounded vesicles. Their fusion supplies new plasma membrane for each of the two daughter cells. Synthesis of a new cell wall between the daughter cells then occurs at the cell plate.

49. Apoptosis
Cell death. Factors that signal genes to produce self destructive enzymes. Not sure why.
EX: webbing of toes on an embryo.

50. Cyclins Protein that controls cell division..
They can make cells grow in a petri dish.
Doesn’t work on all cells.

51. Controls on Cell Division

52. Cancer
Class of disease caused by uncontrolled cell division. Arises when the regulation of the cell cycle breaks down. The cells continue to divide with the absence of internal and external growth factors.
Benign tumor: cancer cells remain in one mass and usually can be removed.
Malignant: cancer cells break away from the cancer cells to other parts of the body.

53. Why are cancer cells so dangerous?
Cancer cells cannot perform the duties needed by the body. Too many cancer cells and the body cannot perform the processes needed to live. A large tumor can apply pressure to other organs and affect the processes of organ.

54. What causes cells to form cancer?
Cancer cells comes from regular cells that have damage in one of the two genes that makes the proteins for cell cycle regulation.
Oncogene: gene that accelerates the cell cycle.
Gene 2 : breaks cell cycle.
A mutation in these 2 genes can be inherited or a carcinogen can cause a mutation in these genes.

55. Causes of Cancer
Carcinogen: Substances known to cause the cell cycle genes to mutate and cell divide uncontollably.
Various forms of cancer have many causes
Smoking
Radiation
Viral infections
The common thread in all cancers is that control over the cell cycle has broken down.
Over 50% of cancer cells have a defect in the p53 gene.

56. p53 antioncogene
p53 is a tumor suppressor gene found mutated in about half of human cancers.
It encodes a gene regulatory protein that is activated by damaged DNA and is involved in blocking further progression of the cell cycle.

57. Oncogenes
SRC, proto-oncogene tyrosine-protein kinase

58. Treatments for Cancer
Radiation and chemotherapy – used to kill the cancer cells and stop division. They kill good and bad cells.

59. Stem Cells Stem cells are a type of body cell that have the ability to
Divide and renew themselves
Remain undifferentiated
Develop into a variety of specialized cells.