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A-level Biology > 20 - Gene expression > Flashcards

20 - Gene expression Flashcards

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1
Q

Give 6 types of mutation.

A

Base substitution, addition, deletion

Gene duplication, translocation, inversion

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2
Q

Give two mutagenic agents.

A

Ionising radiation
Chemicals

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3
Q

Give the types of stem cells, in order of decreasing potency.

A

Totipotent
Pluripotent
Multipotent
Unipotent

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4
Q

How do totipotent cells specialise during development?

A

Only some of their DNA is translated.

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5
Q

How can induced pluripotent stem cells be produced?

A

From adult somatic cells, using protein transciption factors.

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6
Q

What can pluripotent cells differentiate to?

A

Any type of cell, save for extra-emybro cells, such as the placenta

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7
Q

What are cardiomyoctyes?

A

Unipotent stem cells found in the heart muscle, which can generate new cardiomyocytes.

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8
Q

What is stem cell therapy?

A

Introducing stem cells into damaged tissues to treat diseases such as leukemia, or injuries such as burns.

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9
Q

Give a scientific drawback to using stem cells in medical care?

A

Stem cells cultured in labs could become infected with a virus, which could then be transmitted to the patient.

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10
Q

Define a transcription factor.

A

A protein which controls the transcription of genes by binding to a specific region of DNA.

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11
Q

What is the binding site for transcription factors and RNA polymerase?

A

Promoter region

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12
Q

How do transcription factors work?

A

Bind to promoter region
Prevent RNA polymerase binding to DNA
Decrease transcription

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13
Q

What is oestroegn?

A

A steroid hormone

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14
Q

Describe the oestrogen simulation pathway.

A

Oestrogen diffuses through cell and nuclear membrane as it is lipid soluble
Attaches to oestrogen receptor on transcription factor
Alter binding site of transcription factor
Binds to DNA, simulating binding of RNA polymerase and transcription.

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15
Q

What is epigenetics?

A

Heritable changes to gene function, without changes to base sequence of DNA.

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16
Q

What affects the epigenome?

A

Environment

17
Q

What does acetylation cause?

A

Less tightly wrapped DNA
RNA polymerase binds more easily
Gene expressed

18
Q

What is an acetyl group?

A

COCH3

19
Q

What does methylation cause?

A

Methylated (CH3) bases attract proteins that bind to DNA and inhibit transcription

20
Q

Give two genes which control cell division.

A

Proto-oncogenes
Tumour suppressor genes

21
Q

What is RNAi or siRNA?

A

Small interfering RNA

Binds To complete sequence of mRNA.
Cell detects this as double stranded which is abnormal
So enzymes break it down, preventing translation.

22
Q

What is metastasis?

A

The spread of malignant tumours to neighbouring cells.

23
Q

What is an oncogene?

A

Mutated Proto-oncogene which results in uncontrolled cell division, by permanently activating a cell surface

24
Q

What do tumour suppressor genes do?

A

Control cell division by stopping cell cycle when damage is detected.

Apoptosis (programmed cell death)

25
Q

How is oestrogen linked to cancer?

A

Binds to transcription factor which activates genes promoting cell division, leading to tumour formation.

26
Q

How can abnormal methylation if tumour suppressor genes and oncogenes cause cancer?

A

Hyper-methylation of tumour suppressor gene

27
Q

Give an example of an application of determine the genome of simpler organisms. (2)

A

Allows proteome to be determined
Identify potential antigens for using in vaccine production.

28
Q

Why can proteomes not easily be determined for more complex organisms?

A

Presence of non-coding DNA and regulatory genes

29
Q

How do you find the median survival time for a group of patients?

A

Rank in ascending order
Find middle value

30
Q

Give one way in which benign tumours differs from malignant tumours.

A

Benign tumour cells cannot spread to other parts of the body.

31
Q

What is meant by a genome? (1)

A

All DNA in an organism.

32
Q

Determining genome of a virus can allow scientists to develop a vaccine, example how. (2)

A

Identify proteome
Identify potential antigens

33
Q

Suggest and explain how the viruses become able to infect other species of frog. (2)

A

Mutation in viral DNA
Altered viral attachment protein
Allows virus to bind

A-level Biology (21 decks)

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