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P5 3

Koichi

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Chro moso me

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Sta ge s of the cel l cycle cycle

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miss (error) print

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P53

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Li-FraumeniSyndrome LFS LFS 400 LFS ,30 30%,70 90% 50 P 53

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p53 is a protein that functions to block the cell

cycle if the DNA is damaged. If the damage is

severe this protein can cause apoptosis (celldeath).

p53 levels are increased in damaged cells. This

allows time to repair DNA by blocking the cell

cycle.

A p53 mutation is the most frequent mutation

leading to cancer. An extreme case of this is Li

Fraumeni syndrome, where a genetic a defect inp53 leads to a high frequency of cancer in

affected individuals.

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P53 The Guardian of the genome

tum or su ppres sorgene ant ionco gene

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P53 (pro tein) 393 am inoacid 5300 0

http://www.naoru.com/koubo.htm

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P53

http://zh.wikipedia.org/zh-tw/%E7%BB%86%E8%83%9Ehttp://zh.wikipedia.org/zh-tw/%E7%99%8C%E7%97%87http://zh.wikipedia.org/zh-tw/%E5%9F%BA%E5%9B%A0http://zh.wikipedia.org/zh-tw/%E5%8F%98%E5%BC%82http://zh.wikipedia.org/zh-tw/%E5%8F%98%E5%BC%82http://zh.wikipedia.org/zh-tw/%E5%9F%BA%E5%9B%A0http://zh.wikipedia.org/zh-tw/%E7%99%8C%E7%97%87http://zh.wikipedia.org/zh-tw/%E7%BB%86%E8%83%9E

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[ 21 ]

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p53 p53 apoptosis (p53R2)

http://zh.wikipedia.org/zh-tw/File:Apoptosis-zh.png

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http://zh.wikipedia.org/zh-tw/File:Apoptosis-zh.png

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Apoptosis

http://ja.wikipedia.org/wiki/%E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB:Apoptosis_scheme.png

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APC BR CA-1

DP C-4 FH IT p Pa tcded Rb

http://www.naoru.com/p53.htmhttp://www.naoru.com/p53.htm

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P53

53 1

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53 P53 Nat ure Med icine 1996 9 group

Q&A

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Q&AThe Cell Cycle & Mitosis Tutorial

Problem 9: Cancer

The sputum (fluid coughed up from the lungs) of many

smokers contain cells with mutations (errors) in the genes forp53. The smoking induced mutations appear to be an early

signal showing that cancer of the lungs will follow. What is

the likely relationship between early p53 mutation and the

development of lung cancer?A.

p53 with a mutation directly stimulates the growth of canc

cells.B.Mutations

in p53 would prevent abnormal cells from dying by

apoptosis.C.Mutant

p53 triggers the M phase of the cell cycle leading to abnor

.D.p53 causes a cell to enter G0, blocking cell division.

Department of Biochemistry and Molecular Biophysics

University of Arizona

http://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09a.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09a.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09b.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09b.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09b.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09c.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09c.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09d.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09d.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09c.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09c.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09b.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09b.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09b.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09a.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/09a.html

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A.p53 with a mutation directly stimulates the growth of cancer

cells.Incorrect.

p53 can block the cell cycle allowing DNA repair or stimulate apoptosis.

B.Mutations in p53 would prevent abnormal cells from dying by

apoptosis.Correct.

If the mechanism for eliminating abnormal cells is defective, then the cells

will continue to divide and further damage their DNA. This process leads to

cancer. Exposure to sun also causes apoptosis in damaged cells. This produces

the familiar peeling and blistering associated with severe sunburn. Over manyyears, exposure to sun also leads to cancer. It is particularly interesting that

smoke seems to cause a high frequency of p53 mutations

C.Mutant p53 triggers the M phase of the cell cycle leading to abnormal cell

division.Incorrect.

p53 blocks the S phase until a cell can repair damaged DNA.D.p53 causes a cell to enter G0, blocking cell division.Incorrect.

p53 only blocks the cell cycle until a cell can repair its DNA. Then the cycle

continues unless the damage has included production of cancer causing genes.

In this case, p53 in some unknown way stimulates apoptosis

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stress

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