Welcome to Class
12-7 & 12-8
1. Turn in 4 Biomolecule paper
2. Work on STAAR Review Session 2 # 6-10
3. Regulating Cell Cycle Note
4. Research diseases
5. HF: Assigned Vocab
6. Reminder:
- Quiz over cell cycle next class!
- SEM EXAM next week!
- Sem Exam Study Guide on webpage!
Regulating the Cell
Cycle
Why is this even important?
Can we cure cancer?
If we want to cure cancer....
We must understand what causes is.
That means understanding the cell cycle.
Cancer is an illness
where Cell Growth
Uncontrollably or grow
without stopping
Cancer: Uncontrolled Cell Growth
• Cancer cells don’t respond to normal regulatory signals.
• Cell cycle is disrupted.
• Cells grow and divide uncontrollably.
tumor
blood vessel
Cancer Formation: A Closer Look
1. A cell begins to divide
abnormally.
2. Cells produce a tumor and
start to displace normal cells
and tissues.
3. Cancer cells move to other
parts of the body.
What Causes Cancer?
In all cancers, control over
broken down.
the cell cycle
has
Cancer results from a defect in genes that control cell
growth and division.
Cancer Incidence
Treatments for Cancer
• Surgery to remove localized tumor
• Radiation to destroy cancer cell DNA
• Chemotherapy to kill cancer cells or slow their growth
What controls cell division?
Cell cycle regulators
Cyclin
Internal regulators
External regulators
Check out this game over the regulation
of the Cell Cycle at
http://www.nobelprize.org/educational/medicine/2001/cellcycle.htm
l
Also this animation describe the
CHECKPOINTS that occur during the
cell cycle
Checkpoints
There are strict checkpoints in the cell cycle to ensure that
each stage does not start before the last one has
finished. Other checkpoints prevent cells dividing when
their DNA is damaged - either allowing time to repair the
damage or, if the DNA is too damaged, causing cell
death.
Apoptosis
• A process of programmed
cell death
• Important role in structuring
tissues during growth and
development
• Cell undergoes a series
of controlled steps for selfdestruction.
Cancer
= uncontrolled cell growth
When control of the cell cycle fails, cells begin to divide
uncontrollably, resulting in masses and failure of the cells
to perform their normal functions. This condition is called
cancer.
Causes: environmental, genetic, viruses
*Viruses such as HPV, also called human papillomavirus are
known to be linked to cervical cancer.
Cells divide at different rates,
depending on the cell type
--Nerve and muscle cells
usually stop dividing
once developed
--Skin cells divide
frequently as skin is
being replaced
constantly
Healing a Bone
new bone cells
• Cells at the edge of an injury are stimulated to divide rapidly.
• As an injury heals, the rate of cell division slows.
The Discovery of Cyclins
• Scientists found a protein in a
cell undergoing mitosis.
• They injected the protein into a
non-dividing cell.
• A mitotic spindle started to form.
• Cyclins: proteins that regulate
the cell cycle
Regulatory Proteins
Internal regulators:
• respond to events inside the
cell
• let cell cycle proceed only
when certain steps have
already happened
External regulators:
• respond to events outside the
cell
• growth factors: wound healing
and embryonic development
• others cause cells to stop or
slow their cell cycles.
Apoptosis
• A process of programmed
cell death
• Important role in structuring
tissues during growth and
development
• Cell undergoes a series
of controlled steps for selfdestruction.