Download Cancer, Disease of Mitosis PowerPoint

Cancer
A Disease of Mitosis
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Cancer: a Disease of Mitosis
• Cancer is a disease of mitosis – resulting in
uncontrollable mitotic division.
• Cells do not live forever, and they will reach a
point where they will either divide through
mitosis or die through a process
called apoptosis.
• Cancer cells are the exception, these cells do
not die and divide uncontrollably as they
crowd out healthy, productive cells.
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Cancerous Transformation of Cells
• Cancer can have many causes, but most are
thought to be related to carcinogens in the
environment.
– Carcinogens are chemicals that can damage DNA
and interfere with a cell's normal cycle - disrupting
the cells ability to control when and how often it
divides.
• Cancerous transformation results from DNA
mutations to the genes that control the cell
cycle.
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Cancerous Transformation of Cells
• Two types of genes normally control the cell
cycle: proto-oncogenes ), which start cell
division and tumor-suppressor genes which
turn off cell division.
• These two gene-types work together, one
turning on cell division when the body needs
to repair or replace tissue, and the other
turning off cell division when the repairs have
been made.
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Cancerous Transformation of Cells
• If the proto-oncogenes become mutated
(changes to DNA), they can become
oncogenes, genes that lead to uncontrolled
mitosis.
• Mutations in the tumor-suppressor genes
result in the cell not having the ability to turn
off mitosis.
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Normal Vs. Cancer Cell Structure
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Tumor Formation
• Dividing cancer cells accumulate forming a mass
that is called a malignant tumor.
– As the tumor grows larger, cancer cells release growth
proteins that promote the development of new blood
vessels.
– The growth of blood vessels at the tumor site provides
the cancer cells with nutrients and oxygen and takes
nutrients away from normal cells.
– The normal cells are “starved” and their functions are
not carried out.
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Metastasis
– The blood vessels at the tumor site provide a
manner by which cancer cells can “escape” from
the tumor site and travel to other parts of the
body.
– We say that the cancer has metastasized when
cancer cells spread from the original tumor site to
other parts of the body.
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Example: Leukemia
• In the case of leukemia, white blood cells grow
uncontrollably and crowd out red blood cells.
– An individual's ability to deliver nutrients to the
body is significantly reduced.
– The blood’s ability to clot is severely
compromised.
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Leukemia Symptoms
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Questions
1. How does a cancer cell differ from a normal
cell?
2. What is a cancerous tumor?
3. How do cancer cells promote the
development of blood vessels at the tumor
site?
4. How are normal cells affected by the
presence of cancer cells?
5. What is metastasis? How does it take place?
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