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2. A level year 13 > Control of Gene Expression > Flashcards

Control of Gene Expression Flashcards

1
Q

When might gene mutations take place?

A

During DNA replication.

DNA is vulnerable as it is single stranded.
Mistakes may take place in replication.

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2
Q

What happens in an addition gene mutation?

A

An extra nucleotide/base is added.

Causes a frame shift.

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3
Q

What happens in a deletion gene mutation?

A

A nucleotide/bade is removed.

Causes a frame shift.

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4
Q

What happens in a substitution gene mutation?

A

A nucleotide/base is removed and another put in its place.

Does not cause a frame shift.

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5
Q

What is a stem cell?

A

Undifferentiated cells that can divide indefinitely and turn into other specialised cells.

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6
Q

Name four types of stem cell

A

Totipotent
Pluripotent
Multipotent
Unipotent

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7
Q

What is a totipotent stem cell?

A

An undifferentiated cells that can divide indefinitely and specialise into any type of cell

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8
Q

What is a pluripotent cell?

A

An undifferentiated cells that can divide indefinitely and specialise into a any cell type excluding the placenta and embryo

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9
Q

What is a multipotent cell?

A

An undifferentiated cells that can divide indefinitely and specialise into a few types of cell

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10
Q

What is a unipotent cell?

A

An undifferentiated cells that can divide indefinitely and specialise into only one type of cell

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11
Q

Give an example of a unipotent cell

A

Cardiomyocyte

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12
Q

which types of stem cell are found in embryos?

A

Totipotent and pluripotent cells

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13
Q

Give some uses of stem cells

A

Medical therapies eg bone marrow transplants to treat diseases like leukemia
Drug testing on sheets of cells
Research on formation of organs and embryo

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14
Q

How are induced pluripotent stems cells produced?

A

From mature, specialised cells. The cells regains the ability to differentiate through the use of proteins in particularly transcription factors

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15
Q

What is a transcription factor?

A

A protein that controls the transcription of genes so that only certain parts of the DNA are expressed

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16
Q

Describe how a transcription factor work

A

TF moves from the cytoplasm into the nucleus
Bind to promoter region upstream of target gene
Inhibits or promotes the binding of RNA polymerase to the gene. This decreases or increases the rate of transcription

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17
Q

Name a hormone that influences the rate of transcription

A

Oestrogen

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18
Q

Describe how oestrogen influences the rate of transcription?

A

Simple diffusion through membrane into cell (steroid hormone)
Binds to a receptor on the transcription factor to form a hormone-receptor complex
Causes a change in shape of complex
Complex enters nucleus and acts as a transcription factor to inhibit or stimulate the binding of RNA polymerase to the gene

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19
Q

Define epigenetics.

A

A change in the expression of a gene without a change to the base sequence of DNA which can be inherited.

20
Q

Name the epigenetic tag that can bind to histones

A

Acetyl groups

21
Q

Name the epigenetic tag that can bind to cytosine bases on DNA

A

Methyl groups

22
Q

How does increased methylation of DNA affect gene transcription?

A

Addition of methyl to cytosine bases
Prevents transcription factors from binding to the promoter

23
Q

How does acetylation of histones affect gene transcription

A

Acetyl groups are positively charged.
When attached to histone they repel each other
The DNA is less tightly bound to the histone
Allows TF and RNA polymerase to access gene more easily

24
Q

DNA that is tightly packed preventing transcription has been …..

A

silenced

25
Q

What does your epigenome respond to?

A

Environment

26
Q

Decreased gene expression is brought about by….

A

Decrease acetylation
Increased methylation

27
Q

Increased gene expression is brought about by ….

A

Increased acetylation
Decreased methylation

28
Q

Epigenetics has been associated with what type of disease?

A

Cancer

29
Q

What type of molecule is involved in silencing mRNA?

A

siRNA

30
Q

What happens to mRNA during RNA interference?

A

mRNA is cut up to prevent it being translated

31
Q

Double stranded RNA is made and then hydrolysed to make short sections of double stranded RNA. Name the enzyme involved

A

Dicer

32
Q

Once the siRNA is formed what does it bind to?

A

An enzyme
RISC

33
Q

What is unique about the siRNA and the mRNA it is going to silence?

A

Base sequence is complementary

34
Q

RNA interference to regulate gene expression is an example of ….

A

Post transcriptional control

35
Q

Transcription factors to regulate gene expression is an example of ….

A

Pre transcriptional control

36
Q

Name two genes that control cell division

A

Proto-oncogenes and tumour suppressor genes

37
Q

What is the function of a proto-oncogene?

A

Stimulate cell division

38
Q

What is the function of a tumour suppressor gene?

A

Slows down cell division

39
Q

What would happen if a proto-oncogene is mutated?

A

Turn into an oncogene
Uncontrolled cell division

40
Q

What would happen if there was a mutation in a tumour suppressor gene?

A

Uncontrolled cell division

41
Q

Mutations in genes that control cell division cause …

A

Cancer

42
Q

What are oncogenes?

A

Mutate proto-oncogenes

43
Q

How do tumour suppressor genes work?

A

Slow down cell division or tells cells to die

44
Q

What is apoptosis?

A

Programmed cell death

45
Q

What is the consequence of a mutation in a tumour suppressor gene?

A

Stops inhibiting cell division
Cells divide out of control

46
Q

Give a difference between a benign and malignant tumour

A

Benign tumours do not spread to other parts of the body
Cannot invade neighbouring tissues

47
Q

Describe the role of tumour suppressor genes

A

Code for protein that control cell division
Stop the cell cycle when damage is detected
Involved in apoptosis - cell e=death

2. A level year 13 (19 decks)

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