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Cancer Biology > Genetic Origins of Cancer > Flashcards

Genetic Origins of Cancer Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

oncogenes are..

A

genes that have acquired the ability to induce normal characteristics of cancer cells

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2
Q

A normal oncogene is called…

A

a proto-oncogene

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3
Q

2 characteristics of tumor suppressor genes

A
  1. cellular brakes
  2. cannot arrest proliferation when mutated
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4
Q

list the 6 hallmarks of cancer

A
  1. self-sufficiency in growth signals
  2. insensitivity to antigrowth signals
  3. evasion of apoptosis
  4. limitless replicative potential
  5. sustained angiogenesis
  6. tissue invasion and metastasis
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5
Q

the concept of endogenous retroviruses were modeled in

A

the 1970s

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6
Q

the concept of endogenous retroviruses attempted to explain

A

how tumor viruses might initiate numerous cancers that showed no symptoms of viral infections

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7
Q

Have endogenous proviruses been acquired in germs lines of both humans and mammals?

A

no, just in mammals

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8
Q

name a virus that has the potential to cause cancer

A

HPV virus

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9
Q

what is the mechanism of viruses that cause cancer?

A

insertion of a viral oncogene or induction of tissue damage

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10
Q

explain the translocation of the Philadelphia chromosome

A

exchange between ABL gene in chromosome 9 w/ the BCR gene in chromosome 22

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11
Q

which chromosome is known as the Philadelphia chromosome?

A

shortened chromosome 22

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12
Q

the gene product of the philadelphia chromosome leads to the development of what cancers

A

leukemias

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13
Q

list 3 other types of DNA arrangements

A
  1. deletion/ insertion
  2. transpositions
  3. inversion
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14
Q

how do ras mutants result in an active protein

A

by not being able to carry out GTP hydrolysis

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15
Q

what does MAPK stand for

A

mitogen-activated protein kinase

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16
Q

EGF signal transduction is characterized by what 4 characteristics

A
  • GF binding
  • receptor dimerization, cross phosphorylation
  • activation of internal kinase cascade
  • transcription/ gene expression
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17
Q

explain how a truncated receptor leads to deregulated growth factor signaling

A

emits signals even in the absence of ligand binding

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18
Q

what growth factor is suspected in autophosphorylation

A

EGF

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19
Q

what GF is dimerized by a heparin link

A

FGF2

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20
Q

what single molecule simultaneously contacts 2 receptor monomers causing dimerization?

A

EPO (erythropoietin)

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21
Q

what ligand molecules may bind 2 monomeric receptors exposing 2 activation sites?

A

TGFa

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22
Q

what is the effect of GF on platelet cells

A

when activated the secretory vessels containing GF fuse with PM and release mitogens

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23
Q

TRK oncogene is a…

A

chromosomal inversion on the same chromosome (fusion gene)

24
Q

fusion gene of the TRK oncogene causes the

A

receptor region to remain dimerized and its kinase becomes constitutively activated

25
Q

STAT stands for

A

signal transduction and activation of transcription

26
Q

in what pathway of cell proliferation is the kinase not built into the receptor?

A

the Jak-STAT pathway

27
Q

list the 5 different types of abnormalities that can result in proto-oncogenes

A
  1. point mutation
  2. gene amplification
  3. chromosomal translocation
  4. local DNA arrangements
  5. insertional mutagenesis (viral DNA)
28
Q

ras oncogenes differ from their proto-oncogenes by point mutations resulting in…

A

single substitutions at critical positions where Gly is changed for Val

29
Q

what act as brakes that slow down cell cycle progression?

A

proteins encoded by tumor suppressor genes

30
Q

what is known as the prototype of a tumor suppressor gene?

A

Rb

31
Q

what is the target of tumor suppressor genes that is often mutated in a number of different human tumors?

A

cyclin D/ Cdk4,6

32
Q

b/c a single oncogene is requires to produce cancer oncogenes are characterized as

A

exhibiting dominant behavior

33
Q

with tumor suppressor genes _____ copies must become ________ becoming _____ and leading to _____.

A

both
non-functional
recessive
cancer

34
Q

when active Rb binds to E2F transcription factor it prevents:

A

-transcription of genes for DNA replication
- passage from G1 into S phase

35
Q

a phosphorylated Rb can NOT bind to E2F causing…

A
  • E2F to activate gene transcription (onto S phase)
  • dephosphorylated Rb returns to inhibit E2F
36
Q

what type of experiments demonstrate that cancer is of a recessive phenotype

A

cell fusion experiments

37
Q

explain a cell fusion experiment

A

a cancer and normal cell are fused the fused cell divides and the new nuclei contains chromosomes from original cells. results in a hybrid cell w/ normal growth. hybrid cell divides and chromosomes are lost resulting in a cancer cell w/ uncontrolled growth

38
Q

in a cell fusion experiment reversion of the cancer phenotype is due to..

A

the loss of tumor suppressor genes

39
Q

what are the 2 different types of inheritance patterns of mutation genes?

A

recessive cancer-risk syndrome

dominant cancer-risk syndrome

40
Q

in recessive cancer-risk syndrome…

A

2 copies of tumor suppressor genes must be inherited to create a high risk of developing cancer

41
Q

in dominant cancer-risk syndrome

A

a single defective tumor suppressor gene is sufficient to cause high risk of getting cancer, but a second gene is required before cancer can actually arise

42
Q

what allows for functional tumor suppression?

A

heterozygosity

43
Q

what is loss of heterozygosity?

A

when a normal chromosome becomes disrupted bc of the mutated chromosome

44
Q

list the 3 types of loss of heterozygosity

A
  1. mitotic nondisjunction
  2. mitotic recombination
  3. gene conversion
45
Q

explain mitotic nondisjunction

A

duplicate copies of the normal chromosome fail to divide at the time of mitosis causing both copies to go into one cell and the other cell is left with the mutated chromosome

46
Q

explain mitotic recombination

A

2 homologous chromosomes exchanging DNA sequences when lined up during mitosis causing 2 mutant copies of the tumor suppressor gene to end up in the same cell

47
Q

explain gene conversion

A

base sequence information getting copied from one chromosome to another when they’re lined up next to each other. causes the mutant tumor suppressor gene to be copied onto the normal chromosome

48
Q

explain hereditary Rb

A

offspring have a 50% chance of inheriting a defective Rb gene

49
Q

explain nonhereditary Rb

A

cancer only arises if both copies of Rb undergo mutations in the same cell

50
Q

Rb tumors are believed to arise from a

A

multipotent stem cell precurser of multiple types of cells

51
Q

name a type of human tumor suppressor genes that have been cloned

A

RB
NF1

52
Q

NF1 is a _____ ______ of Ras signaling

A

negative regulator

53
Q

NF1 stands for

A

neurofibromatosis type 1

54
Q

neurofibromatosis type 1 is a

A

familial cancer precursor w/ an inherited mutant allele

55
Q

what forms around the cell sheaths of PNS?

A

neurofibromas form around cell sheaths of the PNS

56
Q

NF1 patients are at higher risk for

A

developing additional cancers

57
Q

what drives more than a quarter of breast cancers

A

missing gene

Cancer Biology (15 decks)

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