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8. Control Of Gene Expression > Mutation + Gene Expression > Flashcards

Mutation + Gene Expression Flashcards

1
Q

What are mutations

A

Changes in DNA base sequence

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2
Q

What can insertion or deletion mutations cause

A

Frameshift

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3
Q

What is a duplication mutation

A

One or more bases are repeated producing a frame shift

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4
Q

What is an inversion mutation

A

Group of bases become separated and Rejoin at same position in reverse order

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5
Q

What is a translocation mutation

A

Group of bases separated from DNA on a chromosome and inserted into DNA sequence of another chromosome

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6
Q

Name 3 causes of mutation

A

Spontaneous in DNA replication
Chemical mutagens
Ionising radiation

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7
Q

Why might a mutation not cause a change in amino acid produced

A

DNA is degenerate

Mutation in Intron/non-coding part of DNA

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8
Q

Why might a mutation that changes a Amino acid not have an effect on function of protein

A

Change in tertiary structure does not affect active site

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9
Q

What is a stem Cell

A

Undifferentiated cells which can divide to give rise to any cell type

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10
Q

Totipotent stem cells

A

Can differentiate into any cell type including embryonic cells
- only around during early stage of embryo then and quickly differentiate to make up foetus

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11
Q

Pluripotent stem cells

A

Can form any cell type in body except embryonic cells

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12
Q

Multi potent stem cells

A

Can differentiate into multiple cell types but are more limited

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13
Q

Unipotent stem cells

A

Only differentiate into one type of cell

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14
Q

What can stem cells be used for in health

A

Treat disease by repairing damaged tissue or differentiating into cell types to replace damaged

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15
Q

What are Induced pluripotent cells

A

Come from Unipotent cells eg: skin
Reprogrammed back into unspecialised Pluripotent cells by activating genes using Transcription factors

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16
Q

Why are Induced pluripotent cells useful

A

Reduces need to extract Pluripotent cells from embryo
Reduces ethical concern of embryo use

Reduce chance of rejection as its own body cells

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17
Q

What happens when a cell becomes specialised

A

Only some genes are activated = only activated genes are expressed

If a gene is expressed it is transcribed and translated to produce proteins = differentiation happens as certain proteins are made

The presence of certain proteins makes a cell soecialised

18
Q

What is a gene

A

A section of DNA that can be transcribed into a protein

19
Q

What are transcription factors

A

Produced in cytoplasm + move to Nucleus
Stimulate or inhibits transcription of target genes

20
Q

How do transcription factors activate or repress transcription

A

Interact with RNA Polymerase = allowing it to bind to DNA

Or Stops RNA polymerase from binding

21
Q

What allows Oestrogen to move freely across cell membrane

A

Lipid-Soluble Hormone

22
Q

Describe the action of Oestrogen in initiating Transcription

A

1- Binds to Receptors on Transcription factors in cytoplasm
2- forms a Receptor-Complex Hormone that can now enter the nucleus
3- bind to promoter Region of DNA = stimulates Transcription

23
Q

What does Oestrogen do to allow transcription factor to bind to DNA

A

Binding changes the shape of the DNA binding site on the transcription factor = means it can bind to DNA

24
Q

What is siRNA

A

Small interfering RNA
Small double stranded = unwinds to form a single strand complimentary to mRNA
Prevents translation by breaking down transcribed mRNA

25
Q

How does siRNA break down/ cut up mRNA

A

1- siRNA binds to complimentary sequence on mRNA
2- as mRNA is meant to be single stranded cell detects double strand and views it as Abnormal
3- mRNA is therefore broken down preventing translation

*siRNA has to unwind to become single stranded
* mRNA is cut into small fragments

26
Q

What are epigenetics

A

Gene expression is controlled without changes to base sequence of DNA - shows that environmental factors can affect function of genes

27
Q

What is methylation and the effect of increased methylation

A

Methyl groups added to DNA

Prevents transcriptional factors from binding to DNA by making it tightly wound round histones = factors cannot bind so no transcription

28
Q

What is acetylation and what is the effect of decreased acetylation

A

Adds acetyl groups to histone

Histones are positively charged and DNA is negatively charged = decreased acetylation increases positive charge on histones = DNA bound more tightly = factors cannot access DNA = no transcription + gene switched off

29
Q

To decrease the transcription/ switch off genes what epigenetic changes occor

A

Increase methylation

Decrease Acetylation

30
Q

What is cancer

A

Uncontrolled rapid cell division

31
Q

Benign tumours

A

Grow slowly and dod not spread = does not invade nearby tissue

However does put pressure on body by pressing against blood vessels or other cells

32
Q

Malignant tumours

A

Grows rapidly and spreads to nearby cells = cause damage by damaging bayou tissues + organs
Much more difficult to treat than benign

33
Q

What is metastasis

A

Cancer cells break off from tumour and travel through blood + lymphatic system

34
Q

What are proto-oncogenes

A

Stimulate cell division = produce proteins that cause cells to divide
Produce oncogenes if mutated

35
Q

What are oncogenes

A

Formed from mutated Proto-Oncogenes
= results in genes for cell division permanently switched on = uncontrolled cell division

36
Q

Tumour suppressor Genes

A

Control/ Slow cell division
= produce proeteins that stop cell division
Also play a role in Apopstasis= programmed cell death

When TSGs are switched off cell division is unregulated

37
Q

How might hypermethylation affect tumour suppressor genes

A

No proteins to control cell division produced = cell division is uncontrolled

38
Q

How might increased oestrogen levels be linked to cancer

A

Increased formation of receptor-Hormone complex with transcription factors = increased activation of genes promoting cell division = uncontrolled cell division

39
Q

How might hypo methylation affect Proto-Oncogenes

A

Removal of methyl groups = proto-oncogenes act as oncogenes and cell division is stimulated

Increase in transcription of proteins that cause cell division

40
Q

How do environmental factors such as smoking affect Epigenetics and cancer/tumours

A

Environmental factors affect methylation
Methylation can cause tumour suppressor genes to be silenced or oncogenes to be activated = causing tumour formation

Scientists are developing drugs to reverse Epigenetic changes

8. Control Of Gene Expression (3 decks)

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