Download Cell Cycle and Cancer

January 19, 2017
Journal: What is mitosis? Why is
it important?
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Hand in your homework
The Cell Cycle
The Cell Cycle
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Four Phases
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G1 – Gap 1
S – DNA Replication
G2 – Gap 2
Mitosis
Interphase
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Occurs when the cell is not dividing
Cells spend the majority of their time in this phase
Made up of three phases
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G1 – Growth Phase
S – DNA Replication Occurs
G2 – Growth Phase
Mitosis
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Division of the nucleus
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Occurs in 4 stages: PMAT
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Prophase
Metaphase
Anaphase
Telophase
http://www.stolaf.edu/people/giannini/flashanim
at/celldivision/crome3.swf
1st: Prophase
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The nuclear membrane disappears
2nd: Metaphase
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Pairs of chromosomes line up at the center of
the cell
3rd: Anaphase
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Pairs of chromosomes separate and begin to
move to opposite ends of the cell
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4 :
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Telophase
Two new nuclei form around the
chromosomes
Chromosomes become chromatin (threads
rather than X’s)
Mitosis ends
Cytokinesis
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Last stage of the cell cycle
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Not part of mitosis
Cell membrane pinches inwards to create two
daughter cells – each with its own nucleus
with identical chromosomes
How long does the cell cycle take?
How is the cell cycle regulated?
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Cyclins – proteins that regulate the amount of
time spent at each stage of the cell cycle
Checkpoints
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At the end of each stage cells must pass
through checkpoints to make sure that the
cell is at the appropriate point in the cell cycle
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If not, the cell will be destroyed
When cells that should not pass through the
checkpoint do anyway it results in cancer
What is cancer?
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Cancer is the uncontrolled cell growth of
abnormal cells in the body.
How does cancer occur?
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Step 1: External factors cause mutations in the
DNA
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Can be genetic or caused by carcinogens (cancer
causing agents)
Step 2: Cell loses its ability to control it’s grow and
division
Step 3: Over an extended period of time, a mass of
cells known as a tumor will form
Formation of Tumors
Types of Tumors
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Malignant Tumors
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Fast growing
Likely to metastasize (spread to other parts of the
body and cause problems)
Benign Tumors
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Slow growing and does not metastasize