1. Regulating the cell cycle
Honors Biology Chapter10 Section 3
SC B-2.7: Summarize how cell regulation controls & coordinates cell growth & division & allows cells to respond to the environment, and recognize the consequences of uncontrolled cell division
Regulating the cell cycle

2. Essential Question
How does cancer happen?

3. Cell Cultures Contact Inhibition
Cells in a petri dish with appropriate nutrients will continue to grow until they come in contact with other cells: called
Contact Inhibition

5. Contact Inhibition
similar controls in body
occurs in wound healing

6. Cell Cycle & Its Regulators

7. Cell Cycle Regulators: Cyclins
regulators are cell proteins (cyclins)
regulate timing of cell cycle in eukaryotic cells
dozens other proteins since discovered
Internal Regulators
External Regulators

9. Internal Regulators proteins that respond to events inside the cell
allow cell cycle to proceed once certain processes have been completed inside cell

10. External Regulators proteins that respond to events outside cell
direct rate of cell division
most important ones:
Growth Factors
important in embryonic development
also used in wound healing

11. Uncontrolled Cell Division  Cancer
cancer: disorder in which some of an organisms cells have lost ability to control growth
Cancer cells do not respond to signals that regulate cell division

12. Cancer Cells have Loss of Contact Inhibition

13. Causes of Loss of Control???
appears to have many causes:
carcinogens
some affect internal regulators, some external regulators
defect in gene p53

14. Carcinogens Nicotine Viruses Radiation Hepatitis
Human Papilloma Virus (HPV)
Bovine Papilloma Virus
Tobacco Virus
Radiation

15. Cancer Cells

16. Skin Cells

17. Stomach Cells

18. HeLa Cells
Henrietta Lacks died of cervical cancer in Johns Hopkins Hospital, Baltimore, MD in 1950’s
Biopsies of her cervix taken to Hopkins where they were cultured &they are still growing!

19. HeLa Cells used in multiple medical areas:
development of Polio Vaccine
trip to the moon : What is the effect of weightlessness on rate of cell growth/division ?
cell cloning
gene mapping
hybrid cell lines

20. HeLa Cells