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A-Level Biology > The Conrol of Gene Expression - Gene Expression > Flashcards

The Conrol of Gene Expression - Gene Expression Flashcards

(45 cards)

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1
Q

State all the different types of mutation

A
  • Substitution
  • Addition
  • Deletion
  • Inversion
  • Duplication
  • Translocation
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2
Q

What is a substitution mutation

A

When one base is changed for a different base

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3
Q

Does a substitution mutation result in frameshift

A

No

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4
Q

What is an addition mutation

A

When one or more bases are inserted into the DNA base sequence

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5
Q

Does an addition mutation result in frameshift

A

Yes

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6
Q

What is a deletion mutation

A

When one or more bases are removed from the DNA base sequence

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7
Q

Does a deletion mutation result in frameshift

A

Yes

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8
Q

What is an inversion mutation

A

When a sequence of bases becomes separated from the DNA base sequence and rejoins at the same position but in the inverse order

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9
Q

Does an inversion mutation result in frameshift

A

No

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10
Q

What is a duplication mutation

A

When one or more bases are repeated

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11
Q

Does a duplication mutation result in frameshift

A

Yes

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12
Q

What is a translocation mutation

A

When a section of DNA from one chromosome breaks off and attaches to another chromosome

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13
Q

Does a translocation mutation result in frameshift

A

No

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14
Q

Describe the two features of a stem cell

A
  • Undifferentiated cells
  • Divide indefinitely by mitosis
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15
Q

Totipotent stem cell definition

A

Can divide and differentiate into any type of body cell

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16
Q

Pluripotent cell definition

A

Can divide and differentiate into most types of body cell

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17
Q

Multipoint stem cell definition

A

Can divide and differentiate into a limited number of cell types

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18
Q

Unipotent stem cell definition

A

Can divide and differentiate into only once cell type

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19
Q

When are totipotent stem cells present in an organism’s life

Study These Flashcards
A
  • Early embryo
  • First 4 days as an embryo
20
Q

When are pluripotent stem cells present in an organism’s life

21
Q

When are multipotent stem cells present in an organism’s life

Study These Flashcards
A

Mature mammals

22
Q

Give an example of a unipotent stem cell

Study These Flashcards
A
  • Cardiomyocytes
  • These are heart muscle cells
23
Q

How can a stem cell transplant be used in the treatment of diseases

Study These Flashcards
A

Stem cells can be transplanted to divide and differentiate into the cell type required

24
Q

Advantages of adult stem cells

Study These Flashcards
A
  • No ethical issues
  • Less chance for rejection since similar DNA is used
25
Disadvantages of adult stem cells
- Multipotent, therefore can divide and differentiate into a limited number of cell types - Difficult to isolate
26
Advantages of embryonic stem cells
- Pluripotent, therefore can divide and differentiate into almost all cell types - Easy to isolate since it uses embryos from IVF
27
Disadvantages of embryonic stem cells
- Unethical - High chance of rejection
28
What are iPs (Induced pluripotent stem) cells
Normal specialised body cells that have been reversed back into pluripotent cells
29
How are iPs cells produced
Specialised cells are removed from a patient, and factors are added to make the cell pluripotent
30
What are the Advantages of iPs cells
- Pluripotent, therefore can divide and differentiate into any cell type - A form of longterm treatment - No ethical issues as using own cells - Less chance of rejection
31
- Describe how growth factors can be used in vitro to produce whole plants from plant tissue samples - What characteristic of plant cells allows for this process to occur
- Totipotent plant cells are grown in sterile conditions to produce a mass of undifferentiated plant cells (a callus) - The callus is placed in a growth medium and subjected to specific conditions - Under these conditions, the callus differentiates into specific plant tissues or tiny plantlets, which grow into whole plants - This process can occur since cells in a mature plant are all totipotent
32
Describe the steps by which transcription factors control the expression of target genes
- Transcription factors are proteins - They move from the cytoplasm to the nucleus - They bind to a promotor on DNA - This stimulates RNA polymerase - The gene is transcribed and produces mRNA
33
Describe the steps by which oestrogen initiates transcription
- Oestrogen is lipid soluble, so it crosses the phospholipid bilayer by diffusion - Oestrogen binds to a complementary protein receptor in the cytoplasm - The receptor-oestrogen complex acts as a transcription factor, and it binds to a promotor on DNA - This stimulates RNA polymerase to transcribe the gene and produce mRNA
34
Describe the steps by which siRNA controls gene expression via RNA interference
- siRNA has a specific complementary base sequence to the target mRNA - The siRNA now binds to mRNA molecules by complementary base pairing - The mRNA is destroyed The mRNA can no longer be used in translation and is broken down by enzymes
35
Explain why siRNA is specific to a certain mRNA
They have complementary base sequences
36
Describe the difference between miRNA and siRNA
miRNA is not fully complementary and not specific to one mRNA and therefore targets more than one type of mRNA
37
Define epigenetics
Epigenetics involves the heritable changes in gene function without changing the base sequence
38
Explain how increased methylation affects the expression of genes
- Methyl groups are added to DNA - Transcription factors CANNOT bind to the promotor - RNA polymerase is not activated - The gene is not transcribed
39
Explain how acetylation affects the expression of genes
- The addition of acetyl groups to histone proteins makes chromatin LESS condensed - Transcription factors CAN bind the promotor - RNA polymerase is activated - Transcription DOES occur
40
What is a malignant tumour
- Cells can break off and spread to other parts of the body, forming a tumour elsewhere - Metastasis occurs
41
What is a benign tumour
- Cells do not spread to other parts of the body - No metastasis occurs
42
Describe the function of tumour suppressor genes
Codes for proteins which prevent cell division
43
Describe the function of proto-oncogenes
Code for proteins which stimulate cell division
44
Describe how a mutation in tumour suppressor genes leads to the formation of a tumour
- Stop the formation of proteins, which prevent mitosis - This leads to uncontrolled cell division
45
Describe how a mutation in proto-oncogenes leads to the formation of a tumour
- Mutation of proto-oncogenes to oncogenes - Forms more proteins, which causes cell division - This leads to uncontrolled cell division

A-Level Biology (29 decks)

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