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Biology Y13 > Gene expression > Flashcards

Gene expression Flashcards

1
Q

Mutation definition

A

Change in the DNA base sequence

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2
Q

When in the cell cycle are mutations most likely to occur?

A

Interphase - DNA replication

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3
Q

Name 2 mutagens

A
  1. High energy radiation e.g. UV
  2. Chemicals e.g. asbestos
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4
Q

What are the 5 types of mutation?

A
  1. Deletion/addition
  2. Substitution
  3. Inversion
  4. Duplication
  5. Translocation
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5
Q

Translocation mutation definition

A

Sequence of bases moves from one location on the genome to another

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6
Q

What is a frame-shift mutation?

A

All triplet codes change from the point of mutation

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7
Q

What are the 3 types of substitution mutation?

A
  1. Mis-sense mutation: base change leads to a new amino acid produced
  2. Silent mutation: degenerate
  3. Nonsense: base change leads to a stop
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8
Q

How does a cell differentiate?

A

Certain genes for specific proteins are expressed

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9
Q

Stem cell definition

A

Unspecialised cell which can keep dividing and differentiate into specialised cells

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10
Q

What are the 4 types of stem cell?

A
  1. Totipotent - can divide and differentiate into ANY type of cell
  2. Pluripotent - MOST
  3. Multipotent - LIMITED
  4. Unipotent - ONE
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11
Q

When are the different stem cell types present in an organisms lifetime?

A

Totipotent: first 4 days of embryo
Pluripotent: after 4 days (embryo)
Multipotent: mature mammals
Unipotent: mature mammals

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12
Q

How can stem cells be used in the treatment of disease?

A

Can be transplanted to divide and differentiate into the cell type required

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13
Q

What are the advantages and disadvantages of adult stem cells?

A

Advantages: no ethical issues, less chance of rejection

Disadvantages: multipotent, difficult to isolate

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14
Q

What are the advantages and disadvantages of embryonic stem cells?

A

Advantages: Pluripotent, easy to isolate

Disadvantages: unethical?, high chance of rejection

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15
Q

What are induced pluripotent stem cells?

A

Normal cells which were removed and had factors added to them to make them pluripotent

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16
Q

What are the advantages of induced pluripotent stem cells?

A

• No ethical issues
• Can differentiate into most cell types
• Less chance of rejection

17
Q

How do transcription factors cause transcription?

A

Proteins which bind to a promotor of a gene which stimulates RNA polymerase to transcribe the gene and produce mRNA

18
Q

What are the 2 types of transcription factor?

A
  1. Activators - activate transcription
  2. Recessors - inhibit transcription
19
Q

How does oestrogen act as a transcription factor?

A

Lipid so crosses phospholipid bilayer by diffusion and binds to complementary protein receptor in cytoplasm. Receptor-oestrogen complex binds to promotor which stimulates RNA polymerase etc.

20
Q

How can oestrogen cause cancer?

A

Can cause breast cells to divide more so more likely that mutations occur when DNA replicates so can produce tumours

21
Q

How does siRNA prevent translation?

A
  1. siRNA has specific complementary base sequence to target mRNA
  2. Binds to RISC protein which acts as an enzyme
  3. One of siRNA strands becomes single-stranded
  4. siRNA binds to mRNA molecule by complementary base pairing
  5. mRNA destroyed
  6. Can’t be used in translation
22
Q

How is miRNA different to siRNA?

A

Not fully complementary to one mRNA so targets more than one type of mRNA

23
Q

What is the difference between benign and malignant tumours?

A

Cells in benign tumours can’t metastasise whilst in malignant tumours they can

24
Q

What do tumour suppressor genes do?

A

Code for proteins which prevent cell division

25
Q

What do proto-oncogenes do?

A

Code for proteins which stimulate cell division

26
Q

How can mutations of tumour suppressor genes cause cancer?

A

Changes DNA base sequence, amino acid sequence, tertiary structure which stops production of proteins which prevent cell division –> uncontrolled cell division

27
Q

How can mutations of proto-oncogenes cause cancer?

A

Changes DNA base sequence changes amino acid sequence changes tertiary structure –> become oncogenes which produce more proteins which stimulate cell division –> uncontrolled cell division

28
Q

Epigenetics definition

A

Heritable changes in gene function without a change in DNA base sequence

29
Q

How does the methylation of DNA affect gene expression?

A

Methyl groups added to DNA so transcription factors can’t bind to promotor. RNA polymerase not activated so gene is not transcribed

30
Q

How does acetylation of histone proteins affect gene expression?

A

Addition of acetyl groups makes chromatin less condensed so transcription factors can bind to the promotor. RNA polymerase is activated so gene is transcribed

31
Q

The DNA of which cells needs to be methylated/acetylated in order for offspring to ‘inherit’ their parents environmental effects?

A

Gametes

32
Q

How can the methylation of a tumour suppressor gene lead to cancer?

A

Methyl groups added to tumour suppressor gene so transcription factor can’t bind to the promotor so no transcription so no proteins which prevent cell division –> uncontrolled cell division

33
Q

How can the demethylation of a proto-oncogene lead to cancer?

A

Methyl groups removed from proto-oncogene so transcription factor can bind to promotor so more transcription and more proteins which stimulate cell division –> uncontrolled cell division

Biology Y13 (13 decks)

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