Download Chapter 10 Section 10_3 Regulating the Cell Cycle

Chapter 10: Cell Growth and Reproduction
10.3 – Regulating the Cell Cycle
Mr. M. Varco
Saint Joseph High School
Controls on Cell Division
• Most cells in our body continue dividing until they come into contact
with each other
• In the early 1980s, biologists discovered a protein in cells that regulate
cell division called cyclin
• When cyclin is injected into a non-dividing
cell, a mitotic spindle suddenly develops
Controls on Cell Division
Internal Regulators
• Internal regulatory proteins respond to events inside of the cell
• These proteins prevent the cell from entering anaphase until spindle
fibers have attached to chromosomes
Controls on Cell Division
External Regulators
• External regulatory proteins respond to events outside of the cell, and
direct the speed of the cell cycle
• One important group of external regulatory proteins are called growth
factors
• Growth factors stimulate the growth and division of the cell
Controls on Cell Division
Controls on Cell Death
• Cell death occurs as a result of damage or “programmed” cell death
• Apoptosis is a process of programmed cell death, which results in a
series of controlled steps leading to self-destruction
Cancer: Uncontrolled Cell Growth
• Cancer is a disorder in which body cells loose the ability to control
growth
• Cancer cells do not respond to the signals that regulate the growth of
most cells (i.e. cyclins)
• The result?
uncontrolled cell growth
Cancer: Uncontrolled Cell Growth
• When cancer cells divide uncontrollably, they form a mass of cells in
the body called a tumor
• Cancerous, or malignant, tumors invade and destroy healthy body
tissue
Sharks Do Get Cancer: Tumor Found in Great White
DEC 5, 2013 12:00 PM ET // BY DOUGLAS MAIN, LIVESCIENCE STAFF WRITER
Cancer: Uncontrolled Cell Growth
What Causes Cancer?
• Cancers are caused by defects in the genes that regulate cell growth
and division
• Sources of gene defects include:
- smoking
- radiation exposure
- viral infections
Cancer: Uncontrolled Cell Growth
Cancer: Uncontrolled Cell Growth
Cancer: Uncontrolled Cell Growth
Cancer Treatments
• When a cancerous tumor is localized, it can often be removed by
surgery (ex: skin cancer)
• Alternative cancer treatments include targeted radiation therapy, as
well as chemical compounds (ex: chemotherapy)