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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. Essential Question. - PowerPoint PPT Presentation
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REGULATING THE CELL CYCLE
Honors Biology Chapter10 Section 3SC 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
Essential Question
How does cancer happen?
Cell Cultures
Cells in a petri dish with appropriate nutrients will continue to grow until they come in contact with other cells: called
Contact Inhibition
Contact Inhibition
similar controls in body occurs in wound healing
Checkpoints G1 checks:1. do both daughter
cells have intact nuclei
2. does the cell have what it needs for S phase
G2 checks:1. did replication
of DNA have any major mistakes
2. is this cell ready for M phase
Apoptosis
if either checkpoint finds the cell having major defects process of programmed cell death will be triggered
Cell Cycle & Its Regulators
Cell Cycle Regulators: Cyclins regulators are cell proteins
(cyclins) regulate timing of cell cycle in
eukaryotic cells dozens other proteins since
discovered1. Internal Regulators2. External Regulators
Internal Regulators
proteins that respond to events inside the cell
allow cell cycle to proceed once certain processes have been completed inside cell
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
Tumors
can be:1. Benign ( ”kind”)
normal cells will not spread/kill organism
2. Malignant ( “mal”= evil ) cells abnormal will spread locally or systemically
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
Cancer Cells have Loss of Contact Inhibition
Causes of Loss of Control??? appears to have many causes:
carcinogenssome affect internal regulators, some external regulators
defect in gene p53
Carcinogens
Nicotine Viruses
Hepatitis Human Papilloma Virus (HPV) Bovine Papilloma Virus Tobacco Virus
Radiation some Chemicals
CANCER CELLS
Skin Cells
Stomach Cells
HeLa Cells
Henrietta Lacks died of cervical cancer in Johns Hopkins Hospital, Baltimore, MD in 1950’s
Biopsies of her cervix taken to researchers @Johns Hopkins where they were cultured & they are still growing!
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
