Biology > Gene expression > Flashcards

Gene expression Flashcards

(46 cards)

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1
Q

What is a transcription factor?

A

Proteins that control gene expression by stimulating or inhibiting the transcription of target genes

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2
Q

What does oestrogen bind to and what does it form?

A

Oestrogen receptors - forms an oestrogen receptor complex

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3
Q

What do oestrogen receptor complexes act as?

A

Transcription factors

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4
Q

How does an oestrogen transcription factor act?

A

Only when they are present are the genes transcribed

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5
Q

Where does a transcription factor move into?

A

The nucleus, where it binds to the promoter region

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6
Q

How do transcription factors control gene expression?

A

Only once the factor is bound can RNA polymerase bind

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7
Q

What is a repressor?

A

DNA or RNA binding protein that inhibits the expression of one or more genes by binding to the promoter region

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8
Q

How does a repressor work?

A
  • Transcription factor binds to promoter region
  • Prevents RNA polymerase from binding
  • No transcription
  • No mRNA
  • No protein formed
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9
Q

What is an example of a tumour suppressor gene?

A

p53 gene

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10
Q

What do tumour suppressor genes do?

A

Produce a protein involved in the cell cycle (checkpoint protein) and apoptosis (cell death when necessary)

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11
Q

When tumour suppressor genes are mutated, what are the consequences?

A

Cannot carry out its function properly

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12
Q

When can tumour suppressor genes be mutated only?

A

When both copies get mutation

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13
Q

What are proton-oncogenes?

A

Cause mitosis in presence of a growth factor

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14
Q

What happens when there is a mutation to the proton-oncogene?

A

Turns this into an Onco-gene and so there is mitosis even with no growth factor

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15
Q

What are epigenetic?

A

Heritable change to gene function/expression without a change to the DNA base sequence

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16
Q

What are the 2 types of epigenetic changes?

A

Methylation
Acetylation

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17
Q

What is methylation?

A

A methyl group gets added to CpG (in the promoter region CG repeats)

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18
Q

What does methylation do?

A

Turns off genes

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19
Q

How does methylation turn off genes?

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A

The addition of a methyl group makes it harder for RNA polymerase to bind - reduces transcription

20
Q

What is acetylation?

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A

Where acetyl groups bind to the histones protein

21
Q

What does acetylation do?

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A

Turns on genes

22
Q

How does acetylation turn on genes?

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A

As acetyl groups bind to histones, DNA is wound less tightly so easier for RNA polymerase to bind - increases transcription

23
Q

What is RNA interference?

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A

Bind complementary RNA to mRNA to stop it from being translated/binding to a ribosome

24
Q

What are the types of RNA interference?

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A

Small interfering RNA/microRNA

25
What is small interfering RNA/microRNA used by scientists for?
'knock down' a gene rather than 'knock out' a gene
26
How do the scientists know which small interfering/micro RNA to use?
Identify the mRNA sequence produced from the researched gene
27
How do the scientists make the small interfering/micro RNA?
Create a double stranded complementary sequence that is 21 nucleotides long (this will make it specific to 1 mRNA molecule)
28
How is the small interfering/micro RNA introduced to the cell?
It is injected into it
29
What is the cells response to the small interfering/micro RNA?
As the double stranded mRNA is foreign to the cell - the cell itself adds an enzyme that will break it down to single stranded mRNA
30
Once it is single stranded, what will the small interfering/micro RNA do in the cell?
Binds to the mRNA (that is transcribed from the the specific gene) by specific base pairing
31
Once small interfering/micro RNA has bonded to the specific mRNA, what will it do to it?
Either destroys it by breaking it up OR moves it to storage
32
What is the effect of the small interfering/micro RNA binding to the specific mRNA?
Prevents ribosome from binding No translation No protein
33
What are the 6 types of mutations?
- Addition - Deletion - Substitution - Duplication - Inversion - Translocation
34
What is a duplication mutation?
Duplication of a base sequence
35
What is an inversion mutation?
Base sequence is inverted
36
What is a translocation mutation?
A base sequence is moved elsewhere
37
What are the types of stem cells?
Totipotent Pluripotent Multipotent Unipotent Induced pluripotent
38
What are totipotent stem cells?
Can divide and produce any type of body cell
39
How do totipotent cells cause cell specialisation during development?
They translate only part of their DNA - so cell specialisation
40
What are pluripotent stem cells?
Can divide and produce all cells except umbilical cord and placenta
41
What are multi-potent stem cells?
Can divide to form a limited number of cells
42
What are unipotent stem cells?
Makes 1 type of cell
43
What is an example of unipotent stem cells?
Cardiomyocytes - specialised involuntary cardiac muscle cells that make up the heart tissue and are responsible for its rhythmic contraction
44
What are induced pluripotent stem cells?
Can be produced from adult somatic cells using appropriate protein transcription factors
45
How can small interfering/micro RNA be used against viruses?
Can be created against viral genetic material to cause it to degrade and stop the virus from replicating itself
46
How can small interfering/micro RNA be used against cancer?
Can be created to target mRNA produced by oncogenes, preventing the production of proteins that cause cancer or maintain cancerous growth
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