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Biology unit 5 > Genetic engineering > Flashcards

Genetic engineering Flashcards

1
Q

What are genetically modified organisms

A

Organisms that have had their genomes altered by genetic engineering techniques

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2
Q

Why do scientists develop GMO’s

A

These organisms have a more desirable phenotype

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3
Q

What is a transgenic organism

A

A genetically modified organism that contains recombinant DNA

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4
Q

What is the DNA from another organism that is put in the GMO called

A

Recombinant DNA

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5
Q

What was the first type of organism that was genetically modified and why

A

Bacteria which was engineered to produce the human protein insulin

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6
Q

What is the first step required to create GM bacteria

A

isolate the desired gene which encodes insulin from the genome of an organism (human)

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7
Q

How can the desired gene be isolated

A

Restriction endonuclease enzymes can cut the gene out of the chromosome

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8
Q

What are Restriction endonuclease enzymes

A

A type of enzyme that can cut up DNA at a specific sequence of bases called recognition sites

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9
Q

What are recognition sites

A

Sequences of bases specific to each restriction enzyme that are usually palindromic

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10
Q

What are the 2 types of cuts restriction endonuclease enzymes can make

A
  • Clean straight cuts through both strands of DNA at the recognition site - Cut the 2 DNA strands unevenly, creating sticky ends
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11
Q

What are sticky ends

A

Short regions at the end of DNA that are single stranded and therefor have exposed unpaired nucleotides

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12
Q

In order to transfer the isolated gene into the bacteria what must first be done

A

The gene must be inserted into a plasmid

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13
Q

What is a plasmid

A

A circular length of DNA that is found inside bacteria and able to pass into them

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14
Q

How is the plasmid cut

A

Using the same restriction endonuclease enzymes used to isolate the gene

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15
Q

What does using the same restriction endonuclease enzymes ensure

A

Ensures that the sticky ends of the desired gene and the plasmid are complementary and can therefor anneal to each other

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16
Q

What happens once the plasmid and the desired gene have annealed

A

The DNA of the gene and the plasmid permanently joins together by the enzyme DNA ligase

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17
Q

What does this create when ligase has worked

A

Recombinant plasmid

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18
Q

What is done with the recombinant plasmid

A

It is transferred into the host bacterial cell in a process called transformation.

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19
Q

What can occur once the bacteria has been ‘transformed’

A

It will be able to produce the protein

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20
Q

What is the issue with transformation

A

It is an inefficient process and only around 1% of bacteria successfully take up the plasmid

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21
Q

What is the issue with some bacteria taking up the plasmid but not others

A

Bacteria that don’t take it up are not useful so must be removed

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22
Q

How are bacteria that have taken up the plasmid identified

A

The plasmids contain a marker gene which makes it resistant against an antibiotic. All are then cultured on a petri dish in a medium that contains an antibiotic which kills the bacteria that were not transformed

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23
Q

What will happen to the transformed bacteria that survive the petri dish

A

They will grow colonies which are then cultured in a fermenter. The protein produced by the bacteria is then extracted from the culture and purified

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24
Q

What does the plasmid act as

A

A vector

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25
What is the benefits of using human insulin produced by bacteria over insulin taken from animals
- Human insulin has a lower risk of being rejected from the immune system and lowers the risk of infection - Human insulin is less expensive to obtain than pig insulin which lowers the price of the treatment
26
What is the negatives of using human insulin produced by bacteria over insulin taken from animals
- Many people have ethical concerns about the introduction of human DNA into bacteria - Marker genes for antibiotic resistance may be transferred from GM bacteria to other pathogens as bacteria can transfer plasmids - The ability to genetically modify bacteria could result in the production of more lethal pathogens which could be used in biological warfare
27
What is a way of getting around the issue of antibiotic resistance may be transferred from GM bacteria to other pathogens
They modify GM bacteria so that they are unable to produce an essential nutrient or amino acid and therefor dependant on its presence in the culture medium. This also means GM bacteria cannot survive outside the lab and reducing the chance of them coming into contact with pathogens.
28
How can plants be genetically modified
- Agrobacterium. Tumefaciens - A gene gun - Electrofusion
29
What does Agrobacterium. Tumefaciens do?
It is a bacteria that infects plants and inserts a Ti plasmid which causes the plant to form tumours
30
How are GM plants made with Agrobacterium. Tumefaciens
The desired gene is inserted into the Ti plasmid along with a marker gene (for antibiotic resistance)
31
What does the Ti plasmid become when it has had the desired gene inserted into it
A recombinant Ti plasmid
32
What is done with the recombinant Ti plasmid
It is inserted into the Agrobacterium. Tumefaciens
33
What does the Agrobacterium. Tumefaciens do
Infects the plant and inserts the desired gene and the marker gene into the plant genome. This causes a genetically modified mass of cells to form called a callus
34
What do scientists do with the callus
Ensure it has been successfully genetically modified by growing the callus on a medium containing antibiotics
35
What can then be done with the callus when it has been tested for its genetic modification
The callus can be used to produce many GM plant clones by growing pieces of the callus in a medium containing plant hormones. Each piece of callus will develop leaves and shoots from tiny plants called plantlets
36
What is done with the plantlets
They are potted in soil and will eventually develop into a fully grown GM plant
37
How can plants be modified without the direct use of vectors
Gene guns
38
What does a gene gun do
It shoots small pieces of gold or tungsten into plant cells
39
What are the small pieces of gold or tungsten coated with
The DNA sequence of the desired gene and a marker
40
How is use of gene gun ineffective
Not all plant cells will survive the use of a gene gun or incorporate the DNA into their genomes
41
What is done with the plant cells after the gene gun has been used on them
They are cultured in a medium containing antibiotics and plant hormones and the GM plant cells grow to form a callus
42
What is the callus used to form
Many GM plant clones
43
What is plant Pharming
Where GM plants are developed to produce a specific drug or medical protein
44
Where can the drug or medical protein be produced in the plant
In specific parts such as seeds, leaves or tubers
45
What is done with the plant organs of the GM plant once it is fully grown
They are harvested and the drug or medicinal protein is then extracted
46
What are the uses of plant PHarming
- Can be used as a method of combatting infectious diseases caused by pathogens - They can be used to produce antibodies that are specific to antigens found on a pathogen - They can produce the antigens of specific pathogens which can then be used to develop a vaccine against a specific disease
47
What is the main staple diet for the majority of humans
Plants
48
What is the issue with plants being the main staple diet for the majority of humans
They are vulnerable to disease, pests and adverse environmental conditions such as floods or drought
49
What do crops face competition with
Weeds, for resources, which grow faster and may outcompete them
50
What do the issues to do with crops cause
They reduce the yield and cause farmers financial issues. This may mean that we cant feed the overpopulated planet
51
What is the issue with selective breeding to produce crops with more desirable traits
It is a very slow 'hit or miss' technique
52
What are the advantages of genetically modifying plants
They can be modified to have specific desirable traits
53
What types of genes can be introduced to boost crop yield
- Herbicide resistance - Pest resistance - Disease resistance - Drought or flood resistance - Increased nutritional value - Extended shelf life
54
What are the risks of GM crops
- They contain marker genes for antibiotic resistance - Genes that provide plants with resistance to disease and herbicides may spread onto wild plants - Pests or pathogens could evolve resistance to the pesticide in GM crops - GM crops with resistance to floods or drought may be able to grow in countries that previously did not have a suitable climate - Issues with patenting
55
What is the issue with GM plants containing marker genes for antibiotic resistance
These genes could possibly be transferred to pathogens in the intestine of the consumer
56
What is the issue with Genes that provide plants with resistance to disease and herbicides may spread onto wild plants
Could causes issues such as super weeds
57
How could the risk of Pests or pathogens evolving resistance to the pesticide in GM crops be reduced
By producing GM crops that produce multiple pesticides
58
What are the issues with patenting GM crops
Patents prevent farmers from being able to grow the crops without paying for the seeds. GM crop seeds may be more expensive so the farmers who need them most may not be able to afford them. They may make seeds infertile so farmers cant use seeds from the harvest for growing again and have to buy more
59
What are the methods of genetically engineering animals
- Transfection - Liposomes - Microinjection
60
Describe transfection
Viruses can be used as vectors to insert DNA into animal cells in a process known as transfection
61
What cell has to be used for transfection and why
A fertilised egg cell (zygote) so that the whole animal becomes GM
62
What must first be done in transfection
The desired gene must first be incorporated into the genome of a virus. and the viral genome must be modified so that the virus can enter but not replicate inside host cells
63
Which viruses are used in transfection
Retrovirus or adenovirus
64
What is the benefit of viral genome being modified so that the virus can enter but not replicate inside host cells
It reduces the risk of viral vectors causing disease by damaging the host cells
65
What does the virus do once it has entered the cell
It incorporates its DNA, including the desired gene into the animal genome
66
What is a liposome
A small sphere formed from a phospholipid bilayer
67
How do liposomes GM animals
Many copies of the desired gene is wrapped in the liposomes which are easily able to fuse with animal cell membranes, this results in the delivery of the desired gene into the cytoplasm of the host cell
68
What is the difficulty with liposomes
The DNA then needs to be incorporated into the animal genome which is a challenging and inefficient process
69
Describe a microinjection
It is the process of inserting DNA directly into the nucleus of an animal cell using a very fine micropipette
70
What piece of equipment does a microinjection need and what does it do
Needs a micro manipulator which does the microinjection with greater precision than can be achieved manually
71
What is the issue with microinjections
It is very inefficient as many cells must be injected before one successfully incorporates the DNA into the host genome
72
What are GM animals most commonly used for
PHarming
73
Why may animals be GM instead of bacteria for PHarming
Animals may be better at producing larger more complex eukaryotic proteins
74
Why are mammals most commonly used in PHarming
They can secrete the medically required human proteins in milk
75
Describe the process of GM an animals to produce a specific protein
- Desired gene is introduced into a fertilised female egg cell - The gene contains a tissue specific promoter sequence so that the gene is only expressed in the mammary glands - So when the GM female mammal reaches maturity and gives birth it will start producing milk that contains the human protein which can then be extracted and used for medical applications
76
What can GM animals also be used for
Models in scientific research
77
How do GM animals act as models
They can be GM so that some of their genes are silenced in order to model human diseases caused by faulty genes
78
What is it called when a gene is silenced by genetic engineering
Gene knockout and the animal is called a knockout animal
79
What are knockout mice used for and how
Used as models for cancer by deleting genes involved in regulating cell division. Then these can then be used to test possible cancer treatments
80
What are some ethical issues with GM animals
- Some people may have an ethical issue with the insertion of human genes into animals - Most GM animals die during development as the insertion of a gene can interrupt essential functioning of other genes - GM animals that do survive may have harmful side effects like lameness and susceptibility to stress - Using animals as models of human diseases will negatively effect their welfare

Biology unit 5 (49 decks)

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