1. Mitosis and Cancer You will learn: -Reasons Cells Divide
-Phases of the Cell Cycle
-Abnormal Cell Growth

2. Some reasons why cells divide?
Reproduction
Growth
Repair

3. Limits to Cell Growth
There are two main reasons why cells divide

4. Reason #1
The larger a cell becomes, the more demands the cell places on its DNA
This is called “DNA Overload”

5. Understanding DNA Overload
In eukaryotic cells, DNA is found in the nucleus of the cell. When a cell is small, the information stored in the DNA is able to meet all the needs of the cell

6. As the cell increases in size, it usually does not make extra copies of DNA. The cell’s DNA would no longer be able to serve the increasing needs of the growing cell

7. Reason #2
Food, oxygen, and water enter the cell through its cell membrane. Waste products must leave in the same way.
The rate at which this exchange takes place depends on the surface area of the cell, which is the total area of its cell membrane

8. The rate at which food and oxygen is used up and waste products are produced depends on the cell’s volume
If a cell gets too large, it would be difficult to get sufficient amounts of oxygen and nutrients in and waste products out

9. What is the Cell Cycle?
A period where the cell grows, replicates its DNA, and divides into two daughter cells.

11. Mitosis and Meiosis Mitosis: -division of somatic (body) cells Meiosis
-division of gametes (sex cells)

12. Mitosis
Interphase
Prophase
Metaphase
Anaphase
Telophase

13. Interphase (inter = between)
The "holding" stage or the stage between two successive cell divisions. ~90 percent of a cell's time in the normal cellular cycle may be spent in interphase.

14. Interphase (Longest Part of the Cell Cycle)
technically not part of mitosis, but it is included in the cell cycle
cell is in a resting phase
performing cell functions
DNA replicates (copies)
organelles double in number, to prepare for division

15. Interphase G1 - (Growth 1) S - (Synthesis) - DNA copies
G2 - (Growth 2) - cell prepares for division

16. G1 Phase (Cell Growth) The cell does most of its growing
The cell increases in size
New proteins & organelles are synthesized

17. S Phase (DNA Replication)
Chromosomes are replicated and the synthesis in DNA molecules take place
Key proteins are also synthesized

18. G2 Phase (Prep. for Mitosis)
Shortest of the 3 phases
Many of the organelles and molecules required for cell division are produced

19. M Phase (Mitosis)
The process of cell division begins.

20. MITOSIS
nuclear division
number of chromosomes remains the same

21. Prophase (pro=primary,first)
In prophase, the chromatin condenses into discrete chromosomes. The nuclear envelope breaks down and spindles form at opposite "poles" of the cell.

22. Prophase Key Events Chromatin coils to form visible chromosomes
In animal cells, centrioles begin to migrate to opposite poles
Spindle forms

23. What is chromatin?
When a cell is "resting" i.e. not dividing, the chromosomes are organized into an entangled structure called chromatin

24. Prophase Chromosome pair up! Chromosomes thicken and shorten
-become visible
-2 chromatids joined by a centromere
Centrioles move to the opposite sides of the nucleus
Nucleolus disappears
Nuclear membrane disintegrate

26. Metaphase (meta is like middle)
In metaphase, the chromosomes are aligned at the metaphase plate (a plane that is equally distant from the two spindle poles). 
The spindles form the framework of the dividing cell.

27. Metaphase Chromosomes meet in the middle!
Chromosomes arrange at equator of cell
Become attached to spindle fibres by centromeres
Homologous chromosomes do not associate

29. Anaphase ana=upward,back
The centromeres divide and the paired chromosomes (sister chromatids) move to opposite ends of the cell.

31. Anaphase Chromosomes get pulled apart
Spindle fibres contract pulling chromatids to the opposite poles of the cell

32. Telophase (telo=end)
In this last stage, two distinct daughter cells are formed after the chromatids have migrated to the opposite poles. Cytokinesis is also occurring at this time.

33. Telophase Now there are two! Chromosomes uncoil
Spindle fibres disintegrate
Centrioles replicate
Nucleur membrane forms
Cell divides

36. Cytokinesis Cyto =cell Kinesis=movement
The cell’s cytoplasm divides at the end of telophase
Animals - cell pinches inward
Plants - a new cell wall forms between the new cells

37. Results of Mitosis The cell is the most basic unit of organization
In animals…
cells-->tissue-->organs-->organ systems
-->organisms

38. The Cell Cycle
Proteins called cyclins and enzymes that attach to the cyclins and become activated control the cell cycle

39. CANCER IS
UNCONTROLLED MITOSIS!

40. What is abnormal cell growth?
Also called uncontrolled, rapid cell growth is a central feature of cancer.
Virtually every cancer is caused by mutations of DNA
Genes that regulate cell division are most susceptible to mutations, which may lead to abnormal cell growth.

41. Tumors Tumors are abnormal growth of cells
Benign tumors are non cancerous and and only grow locally
Malignant tumors are cancerous and spread to other areas of the body

42. Abnormal Cell Growth

43. Abnormal Cell Growth

44. Surgical Removal of Tumor

45. A Large Abdominal Tumor

46. Body without Tumor

47. Cancer Occasionally, cells lose control of the cell cycle
This results from:
failure to produce certain enzymes,
the overproduction of enzymes
Or the production of enzymes at the wrong time.

48. Cancer
Cancer is a malignant growth resulting from uncontrolled cell division
Malignant =dangerous to health; marked by uncontrolled growth

49. Cancer Cancer is the second leading cause of death in the U.S.
Lung, colon, breast, and prostate cancers are the most prevalent types

50. Causes of cancer Genetics Environmental Factors Cigarette smoke
Air and water pollution
Exposure to UV radiation
However, there are still unknown causes and researchers are working to discover these factors.

51. Cancer prevention Healthy Lifestyle Low fat, high fiber diet Exercise
Not smoking
Taking daily vitamins and minerals
Carotenoids, Vitamins A, C, E, and calcium

52. Cancer
Cancer is difficult to treat in later stages because the cancer may have spread to vital organs and damaged them beyond repair.