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BIOSCI 107 > L11 - Mutations And Cancer > Flashcards

L11 - Mutations And Cancer Flashcards

1
Q

Mutations

A
  • Responsible for diversity of genes found among organisms

- can have major, minor, positive or no effects on resulting protein structure and function

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2
Q

Mutation locations

A 
In body:
- germ line: passed on
- local/somatic: not whole body
In DNA:
- protein-coding region
- introns
- 5’/3’ UTR
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3
Q

Types of mutations

A
  • large scale alterations: chromosomal rearrangements

- small scale alterations: one or few nucleotides

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4
Q

Types of small scale alterations

A

Substitution, indels

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5
Q

Types of substitution mutation

A

Silent, mis-sense, nonsense

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6
Q

Indels - 1 or 2 nts

A

Causes frameshift

Could lead to truncated protein

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7
Q

Truncated protein

A

Shortened protein due to premature STOP codon

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8
Q

Indels - 3 nt-pair

A

Maintained frameshift

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9
Q

Wild-type beta-globin

A

5’ GAG 3’
- Glu - (acidic, -ve charge)
Normal hemoglobin
RBC: maximise surface area, flexible - can squeeze through tiny capillaries

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10
Q

Sickle-cell beta-globin

A

5’ GUG 3’
- Val - (hydrophobic)
Sickle-cell hemoglobin
RBC is more rigid - can get clogged more easily in capillaries

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11
Q

Sickle cell anaemia

A
  • Missense substitution mutation

- result of accumulative effect: needs to happen to enough hemoglobins in RBC

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12
Q

Importance of checkpoints

A

Appropriate molecular regulation of cell division critical for normal growth, development and maintenance

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13
Q

Maturation promoting factor (MPF) function

A

phosphorylates many other proteins and allows mitosis to commence

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14
Q

Maturation promoting factor (MPF) composition

A

Specific complex of cyclin and cyclin dependent kinase (CDK)

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15
Q

Cyclin

A
  • Protein fluctuating throughout cell cycle

- Many different forms - e.g cyclin D, E, A, B

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16
Q

Cyclin dependent kinase (CDK)

A
  • Kinase that is phosphorylated/activated when attached to cyclin
  • Many types
17
Q

Stop and go signals

A

Gene products associated with checkpoints

18
Q

Go signals

A

Genes that normally stimulate cell proliferation

19
Q

Stop signals

A

Genes that normally keep proliferation in check (inhibition)

20
Q

If stop/go don’t work correctly due to mutation

A

Uncontrolled cell growth (cell escaped cell cycle control) and can result in tumours

21
Q

Cancer

A

Mutation in regulatory genes in somatic cells = uncontrolled cell division for that cell = can eventually lead to cancer

22
Q

Types of cancer-causing mutations

A

Genetic predisposition, acquired

23
Q

Genetic predisposition

A

In ALL CELLS of body

  • inherited or de-novo
  • issue/deficiency in a gene (typically one copy)
  • doesn’t guarantee cancer but higher risk due to being further along path
24
Q

Acquired

A

Locally and initially in ONE CELL

- due to environmental mutagens (E.g UV damage, smoking, carcinogens, viruses, drugs, treatments)

25
Q

Go signal specific to cancer

A

Proto-oncogenes
- mutation causes proto-oncogenes to become oncogenes
= over-activation (render them constitutively active) = uncontrolled + accelerated cell growth

26
Q

Proto-oncogene examples

A

Ras (GTPase in G protein), Myc (transcription factor)

27
Q

Stop signals specific to cancer

A

Tumour suppressor genes
- mutation causes deactivation (no longer function)
= no inhibition of division of cells with damaged DNA
= uncontrolled cell growth

28
Q

Examples of tumour suppressor genes

A

P53/TP53 (most common cancer-causing mutation, transcription factor), BRCA1/BRCA2 (associated with breast cancer + other cancer types)

29
Q

Pathway to cancer

A

Typically, multiple mutations (1-10) within the same cell are required for it to become fully cancerous

30
Q

Biopsy

A

Sample tumour itself to see possible cancer-causing mutations within
- blood samples are not as useful for tumours/solid tumours

31
Q

Ras (proto-oncogene) normal function

A

1) ligand binds to receptor
2) Ras activated with ATP
3) protein kinases activated
4) transcription factor responds (activator)
5) protein that stimulates cell cycle produced (GO)

32
Q

Mutated Ras (oncogene) function

A

1) no ligand bound but Ras activated
2) DNA transcribed via signal transduction when it shouldn’t
3) overexpression of GO protein

33
Q

P35 (tumour suppressor gene) normal function

A

1) DNA damaged (by UV light)
2) protein kinases activated
3) P35 transcription factor activated
4) protein that inhibits cell cycle made
5) damaged DNA not replicated

34
Q

Mutated P35 function

A

1) DNA damaged (by UV light)
2) protein kinases activated
3) P35 transcription factor NOT activated
4) inhibitory protein absent
5) damaged DNA replicated

BIOSCI 107 (15 decks)

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