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biology factual recall questions > the control of gene expression > Flashcards

the control of gene expression Flashcards

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1
Q

Give six examples of gene mutations

A 
Substitution
Deletion
Addition
Duplication
Inversion
Translocation
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2
Q

What effects do mutagenic agents have on the rate of mutation

A

Increase

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3
Q

What can mutations result in

A

A change in the sequence of amino acids

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4
Q

When mutations only change one codon, why does this sometimes have no effect on the polypeptide coded for

A

DNA code is degenerate

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5
Q

What is a frame shift

A

When a mutation causes all the amino acids after the site of mutation to change

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6
Q

What are base analogues

A

A chemical that can substitute for base in DNA

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7
Q

What are totipotent cells

A

Cells that can specialise into any type of body cell

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8
Q

What are pluripotent cells

A

Cells that specialise into any type of body cell, except placental cells.

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9
Q

What are multipotent/unipotent cells

A

Multipotent Cells can become more than one cell type eg adult stem cells

Unipotent - specialised, can only become one type of cell eg epidermal skin cells

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10
Q

What causes cell specialisation

A

Only part of the DNA is transcribed and translated

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11
Q

how often can pluripotent cells divide

A

unlimited number of times

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12
Q

How are unipotent cells involved in the heart

A

The heart has a supply which are used for repair (Cardiomyocyte)

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13
Q

How are iPS cells created in the lab

A

Scientist take specialised adult cells and “reprogram” them to express transcription factors normally associated with pluripotent stem cells

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14
Q

What is the name of the site at which activators and repressors bind

A

promotor sites

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15
Q

How do Activators effect RNA polymerase binding

A

they make it easier

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16
Q

How do repressors effect RNA polymerase binding

A

they make it more difficult/stop it happening

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17
Q

What type of transcription factor is oestrogen

A

Activator

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18
Q

Give two examples of epigenetic control of gene expression and briefly outline each

A

Increased Methylation - Methyl group attaches to CpG site. This changes DNA structure so the gene is not expressed.
Decreased Acylation - when histone proteins are acylated it is easier for the DNA to be transcribed and the genes to be expressed. Less acylation means the DA is more tightly bound and thus it is harder for the DNA to be transcribed

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19
Q

Can epigenetic changes be passed to offspring

A

Yes

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20
Q

What causes epigenetic changes to DNA

A

Environmental factors

Disease

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21
Q

How does an error in epigenetic control of gene expression link to cancer

A

Abnormal methylation of tumour suppressor genes/protooncogenes prevents them from functioning as they should and allows uncontrolled cell division

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22
Q

Why are epigenetic causes of disease a good target for drugs

A

They are reversible

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23
Q

What is the role of RNAi

A

RNAi prevents m RNA strands from being translated into proteins. It does this by physically blocking translation, before moving the mRNA to a processing body to be degraded or stored

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24
Q

Where in cells does RNAi target the mRNA

A

Cytoplasm

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25
What is a tumour
A mass of abnormal cells
26
What do tumour suppressor genes and protooncogenes both do
Tumour suppressor genes produce a tumour suppressor protein that prevents cell division or causes apoptosis. Protooncogenes produces a protein that enables cells to divide at a controlled rate
27
if a mutation occurs in the protooncogene, what happens
The gene becomes over active and produces lots of proteins that cause uncontrolled cell division
28
What is a mutated protooncogene called
A mutated protooncogene is called an Oncogene
29
What are the differences between malignant and benign tumours
Malignant tumours are cancerous, grow rapidly and invade surrounding tissue. Cells can break off and spread through the body
30
If the tumour suppressor genes become hyper methylated, what happens and how does this link to tumour formation
The genes that code for tumour suppressor protein are not transcribed. This means cells division increases
31
Give two theories as to how increased oestrogen levels link to breast cancer
It stimulates breast cells to divide. More divisions mean more chance of cancerous cells forming. oestrogen may be able to induce mutations directly in cells
32
How does sequencing the proteome of pathogens help with the formation of vaccines
It allows identification of the antigens on the pathogens surface
33
Why is it harder to determine the proteome of humans than of bacteria
Humans have introns and regulatory genes
34
What feature of the genetic code, as well as transcription and translation mechanisms means that recombinant DNA technology only requires the transfer of DNA fragments
They are universal
35
Give three methods of manufacturing DNA fragments
Using reverse transcriptase Using restriction endonuclease enzymes using a gene machine
36
What enzymes cut DNA strands and leave sticky ends
restriction endonuclease
37
Why is it beneficial for DNA strands to have sticky ends
To enable them to be inserted into a complementary section of a vector
38
What is the difference between in Vivo and in vitro gene cloning
In vivo cloning is where copies of the DNA fragment are made inside a living organism. This is done by transforming the host cell and then identifying the host cells which have taken up the DNA. In Vitro uses the Polymerase Chain Reaction to make millions of copies in just a few hours
39
What is a vector
Something used to transfer DNA into a cell
40
Give two examples of vectors
Plasmids | Bacteriophages
41
Name the enzyme used to stick the DNA fragment to the vector DNA
DNA ligase
42
Outline a method for identifying which cells have taken up a vector and its DNA
Insert a marker gene for GFP into the vector DNA. Transformed bacteria will possess the green florescent protein and subsequently will glow florescent green
43
Why are promotor and terminator regions added to the DNA of vectors
To allow the transformed host cells to produce proteins coded for by the DNA fragment
44
Outline the polymerase chain reaction
A mixture is set up containing DNA sample, free nucleotides, primers and DNA polymerase. heated to 95 degrees C to break the hydrogen bonds between the DNA strands cooled to 50-60 degrees C so primers can bind. The mix is heated to 72 degrees C so DNA polymerase can line up free nucleotides alongside the template and form new complementary strands 2 new copies of the fragment of DNA are formed and one cycle of PCR is complete
45
Give a benefit of transformed organisms in agriculture
Increased crop yield | Crops produce more vitamins/nutrients
46
What is the difference between somatic and germ line gene therapy
Germ line is done on sex cells. This means every cell of any offspring produced from these cells will be affected and they will NOT suffer from the disease. This is currently illegal in humans Somatic is done on adult cells particularly targeting the cells that are most affected by the disorder. Eg cystic fibrosis is damaging to the respiratory system so somatic therapy for CF targets the epithelial cells lining the lungs. This therapy does not affect the sex cells so any offspring could still inherit the disease
47
If a disease is caused by a dominant allele, how would you use recombinant DNA technology to prevent it being expressed
Insert "junk" DNA into the dominant allele to prevent it form functioning
48
What are DNA probes
Short strands of DNA. They have a specific base sequence that is complementary to the base sequence of part of the target allele so can be used to locate specific alleles of genes eg on chromosomes
49
What is attached to a DNA probes
A label
50
List 3 uses of screening with DNA probes
Identify inherited conditions determine how a patient will respond to drugs Identify health risks
51
What is a VNTR
A non-coding base sequence that repeats over and over
52
Why do different VNTRs travel different distances in gel electrophoresis
Longer ones are heavier and so travel less distance
53
List two uses of genetic fingerprints
Determining who the father of a child is | identifying if a person committed a crime
54
Name the steps involved in In Vivo amplification
Copies are made inside a living organism 1) The DNA fragment is inserted into a vector 2) The vector transfers the DNA fragment into Host Cells 3) identifying transformed host cells (only 5% host cells take up vector /dna so important. Markers are antibiotic resistance or flurescence
55
How does In Vitro amplification work
Done outside a living organism using the polymerase chain reaction
56
How much dna is made during each PCR cycle
Each cycle doubles the amount made ie 1st 2x2=4 dna fragments. 2nd 4 x2 = 8 dna fragments etc
57
If a disease is caused by two mutated recessive alleles how do you alter the genes using gene therapy
You add a working dominant allele to make up for them - you supplement the faulty ones
58
Give examples of how DNA probes are used in screening
Inherited conditions - Huntington’s disease or cystic fibrosis Determine how a patient will respond to drugs - breast cancer caused solely by mutation in HER2 protooncogene can be treated with Herceptin Helps identify health risks - which helps people make informed choices that could reduce the risk of them developing the disease
59
Ethical problems with screening using DNA probes
It might lead to discrimination by insurance companies or employers if people are know to have a high risk of developing a condition
60
What is a primer
A short piece of DNA that is complementary to the base at the start of the fragment you want
61
How might using recombinant DNA technology benefit people
1) Agricultural crops could be produced more efficiently to reduce the risk of famine - drought resistant 2) Transformed crops could be used to produce useful pharmaceutical products eg vaccines available in areas where refrigeration’s (usually needed to store vaccines is not available) 3) medicines could be produced more cheaply and in large quantities and without using animals eg insulin used to come from animals but now human insulin is made using a cloned human insulin gene 4) it has the potential to treat human diseases using gene therapy
62
What are some of the concerns about using recombinant DNA technology in agriculture
monoculture - where a farmers only plants one type of crop making them vulnerable to the same disease as all the plants are genetically identical. Reduction in biodiversity Possibility of super weeds if transformed crops interbreed with wild plants Contamination of organic crops by wind blown seeds which would mean organic farmers would not be able to sell their crops
63
What are some of the concerns about using recombinant DNA technology in Industry
A few large biotech firms control some forms of genetic engineering. As the use of this technology increases these companies get bigger making it harder for small companies to compete. Anti globalisation protesters think this is bad Without proper labelling consumers may not have a choice as to whether or not they eat GM food
64
What are some of the concerns about using recombinant DNA technology in medicine
Companies who own genetic engineering technologies may limit the use of technologies that could be saving lives Some people worry that this technology could be used unethically eg making designer babies - currently illegal.
65
What does VNTR stand for
Variable number tandem repeats
66
What is a VNTR
Base sequences that don’t code for proteins and repeat over and over
67
The number of times a persons VNTR sequences repeats is unique, how does this relate to nucleotides
The length of these sequences in nucleotides differs too
68
What is a genetic fingerprint
A unique way of identifying someone using patterns in their DNA from VNTR
69
How to make a genetic fingerprint (simple)
``` Sample of dna taken PCR used to produce DNA fragments Fluorescent tag added DNA fragments undergo electrophoresis DNA fragments are then viewed as bands under UV light ```
70
Define Electrophoresis
Separates DNA Fragments to make a genetic fingerprint
71
Steps of electrophoresis
DNA mixture is placed into a well in a slab of gel and covered in a buffer solution that conducts electricity An electrical current is passed through the gel. DNA fragments are negatively charged so they move towards the positive electrode at the far end of the gel Small DNA fragments move faster and travel further through the gel so the DNA fragments separate according to size
72
Are DNA fragments positively or negatively charged
Negative

biology factual recall questions (9 decks)

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