1. Regulating the Cell Cycle
Biology 392
Chapter 10-3

2. Cancer One in three people will develop cancer.
One in four people will die of cancer.
More than 1500 Americans died each day of cancer this year.
Over 1,000,000 cases of skin cancer will be diagnosed this year.
Cancer is the leading cause of death among Americans under the age of 85.

3. What is Cancer?
Disorder in which some of the body’s cells lose the ability to control growth
100’s of different types
Do not respond to internal &/or external signals
Continuously divide – forming masses of cells called tumors.
Cancer cells can break from a tumor and spread throughout the body (metastasize)

4. Can you die from skin cancer?

5. What’s happening in the petri dish?
Section 10-3
How does this represent the healing process?
This is normal  the cells eventually stop

6. What causes the cell cycle to continue. Is it automatic
What causes the cell cycle to continue? Is it automatic? Does it ever stop?

7. Cell Cycle Rates
Cells do not move through the cell cycle at the same rate
Cells in a developing embryo replicate rapidly- 3 minutes
Average time of cell cycle- 20 hours
Lining of esophagus- 2-3 days
Lining of small intestine- 1-2 days
Lining of large intestine- 6 days
Red blood cells-120 days
White blood cells- 10hrs-decades

8. Hypothesis: Substance X will cause a cell to start mitosis Substance X = CYCLIN
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.
Cyclin  cellular protein that regulates the timing of the cell cycle in eukaryotic cells;
 help create spindle

9. Cell Cycle Regulators INTERNAL EXTERNAL
Proteins that respond to signals inside the cell
Checkpoints during interphase:
Make sure all DNA has been properly made
Make sure all chromosomes have attached to a spindle
EXTERNAL
Proteins that respond to events outside the cell
Speed up or slow down cell cycle
Respond to environment and “crowding”

10. Cell Cycle Regulators

11. Causes of Cancer Environment  sun, chemicals
Not exercising  obesity is linked to several
Genetics (but not necessarily inherited)
Mutations in genes that regulate cell cycle
Example:
p53  gene responsible for halting the cell cycle until all chromosomes have replicated properly
 Defects in this gene is a precursor to cancer

12. Progression of Cancer NORMAL CELLS
fast dividing cells, not really toxic, only cause mechanical damage
BENIGN
toxic, cause local toxicity and inflammation
MALIGNANT
METASTATIC
travel from one place to another. The real killer

13. Kinds of Cancers SOLID TUMORS
Carcinomas  originate from surface cells (skin, wall of intestine, surface of organs)
Sarcomas  bone, cartilage, fat, muscle
“LIQUID” TUMORS
Leukemias  circulate in blood stream, from blood
Lymphomas  developed in lymph system

14. 2006 Estimated US Cancer Deaths*
Men 291,270
Lung & bronchus 31%
Colon & rectum 10%
Prostate 9%
Pancreas 6%
Leukemia 4%
Liver & intrahepatic 4% bile duct
Esophagus 4%
Non-Hodgkin %
lymphoma
Urinary bladder 3%
Kidney 3%
All other sites %
Women 273,560
26% Lung & bronchus
15% Breast
10% Colon & rectum
6% Pancreas
6% Ovary
4% Leukemia
3% Non-Hodgkin lymphoma
3% Uterine corpus
2% Multiple myeloma
2% Brain/ONS
23% All other sites
Lung cancer is, by far, the most common fatal cancer in men (31%), followed by colon & rectum (10%), and prostate (9%). In women, lung (26%), breast (15%), and colon & rectum (10%) are the leading sites of cancer death.
ONS=Other nervous system.
Source: American Cancer Society, 2006.

15. Treatments Surgery – remove the affected cells
Radiation – high-dose X-rays kill cells
Chemotherapy – drugs kill cells
Hormone therapy – hormones stop cell growth

16. Video links http://video.about.com/cancer/Chemotherapy.htm
(lung cancer and CT scans)