L25 Tumour suppressor genes Flashcards

1
Q

Tumour suppressor genes

A

control cell cycle
loss of activity => uncontrolled cell division
p53

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2
Q

Oncogenes

A

promote cell division
overactive => uncontrolled division
myc gene

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3
Q

Mutations can lead to cancer

A

need balance between p53 and myc, balance between tumour suppression and cell division genes

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4
Q

overexpression of myc oncogene

A

causes tumours in fish

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5
Q

Mitogen - myc - retinoblastoma

A

see onenote

mitogen stimulates cell cycle entry

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6
Q

DNA damage - p53

A

see onenote slides

p53 blocks cell cycle if myc is overactive
=> cell cycle arrest or apoptosis

p53 phosphorylated => becomes active
p53 activates p21 gene
p21 is a CKI

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7
Q

Multiple avenues to inactivating the second allele of TP53

A

therefore factors/accidents decreasing precision of cell cycle increase chance of inactivating function

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8
Q

Peto’s paradox

A

risk of developing cancer should theoretically increase with both the number of cells and the lifespan of an organism

BUT humans with more cells than mice, live longer

cancer is not the major cause of mortality for large and long-lived wild animals despite increased theoretical risks

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9
Q

Peto’s paradox - one solution?

A

African elephants contain 40 copies of the p53 genes

extra copies of p53 gene may enable elephants to kill off potentially cancerous cells before they form tumours

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10
Q

Peto’s paradox - one solution?

A

African elephants contain 40 copies of the p53 genes

extra copies of p53 gene may enable elephants to kill off potentially cancerous cells before they form tumours

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11
Q

Cancer

A

caused by mutations that may be inherited, induced by environmental factors or result from DNA replication errors (R)

found that R mutations responsible for 2/3 of mutations in human cancers

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12
Q

Naked mole rats

A

defy biological law of ageing

  • rarely get cancer, resistant to some types of pain, can survive up to 18 minutes without oxygen
  • risk of death doesn’t go up as they grow older
  • very active DNA repair and high levels of chaperones
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