Genetic Engineering

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What is genetic engineering?
The manipulation of an organism's genome to achieve a certain outcome
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What is a transgenic organism?
An organism carrying a gene from another organism
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What is the most common technique used to isolate the desired gene?
The use of enzymes called endonucleases
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What are the 2 types of endonucleases?
Ones that make clean cuts creating blunt ends and those that cut the DNA strands unevenly resulting in sticky ends
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What is another technique that can be used to isolate the desired gene?
Isolating the mRNA for the desired gene and using the enzyme reverse transcriptase to produce a single strand of complimentary DNA to the desired gene
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Name an advantage of using mRNA and reverse transcriptase to isolate the gene
It is easier to identify and isolate the desired gene as particular cells will make specific types of mRNA, e.g. Beta cells in pancreas will make a lot of insulin mRNA molecules
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What is a vector?
A carrier of something, in GE it is used to transfer the desired gene into the host cell
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What is the most common vector used in genetic engineering?
Bacterial plasmids- small circular DNA molecules separate from the chromosomal DNA that can replicate independently
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What is the molecule that forms from a plasmid merging with the host cell called?
Recombinant DNA
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Why do certain plasmids get picked?
Because they contain what is called a marker gene which helps scientists determine if the bacteria has taken up the plasmid
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How is the DNA fragment inserted into the plasmid?
The same restriction endonuclease that was used to isolate the DNA fragment is used to also cut the plasmid so they have complementary sticky ends, 2 sticky ends lined up and the enzyme DNA ligase forms phosphodiester bonds joining them together
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Why are the plasmids usually given a second marker?
To show if the plasmid contains the recombinant gene, the marker itself is placed in the plasmid through genetic engineering methods as well
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What other types of markers can be added? And why do we tend to use these markers now instead of antibiotic resistant ones?
Genes that produce fluorescence (from jellyfish) or genes that produce enzymes that causes a colour change in a particular medium, these are more widely used due to the concerns about antibiotic resistance in genetically engineered organisms
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What is the transformation process?
Transferring the plasmid with the recombinant DNA into the host cell
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Describe a method used to transfer the plasmid into the host cell (bacteria)
Culture the bacteria and the plasmids in a calcium-rich solution and increase the temperature, this causes the bacterial membranes to be more permeable and the plasmids can enter
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What is electroporation?
Another method of transferring the plasmids into the bacteria cells, a small electric current is applied to make the bacterial membranes more permeable and so they take up the plasmids
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What else can electroporation be used for?
Getting DNA fragments directly into eukaryotic cells, the current makes the membranes more permeable and so the DNA fragments can move into the nucleus and fuse with the nuclear DNA, has to be carefully controlled as currents can permanently damage
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What is electrofusion?
Another way of producing genetically modified cells, tiny electric currents are applied to 2 different cells, this fuses the 2 different cells together forming a hybrid or a polyploid cell, containing DNA from both
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What is the problem with using electrofusion with animal cells?
Animal cells do not fuse as easily as their membranes have different properties and also the polyploid cells tend not to survive in the body of a living organism
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What is electrofusion used for?
Usually to produce successful GM plants & producing monoclonal antibodies
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How is a monoclonal antibody produced?
By fusing an a cell producing a specific antibody with a tumour cell, meaning it divides rapidly in culture
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What are monoclonal antibodies used for?
Certain treatments, e.g. some forms of cancer, and to identify some forms of pathogens in animals and plants
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Name some examples of substances produced by GM prokaryotes
Hormones (e.g. inulin, HGH), clotting factors for haemophiliacs, antibiotics, pure vaccines and many enzymes used in industry
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Describe a method used to genetically modify plants
Part of plant exposed to bacteria (A. Tumefaciens, forms tumours in plants) with desired gene & AB resistant gene, bacteria deliver gene to plant cells, plant exposed to antibiotic that kills cells lacking new gene, cells multiply & callus if formed
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What happens once a callus is formed?
Callus grows shoots and roots and it is transferred to soil where is can grow to be a fully developed GM plant
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What is another method of producing GM plants?
Electrofusion- removal of cell wall by cellulases, electrofusion to join 2 cells, use of plant hormones to stimulate growth of cell wall again, followed by a callus formation and the production of many cloned transgenic plants
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Why is genetic engineering harder in animal cells?
The membranes of animal cells are a lot harder to manipulate
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Other cards in this set

Card 2

Front

What is a transgenic organism?

Back

An organism carrying a gene from another organism

Card 3

Front

What is the most common technique used to isolate the desired gene?

Back

Preview of the front of card 3

Card 4

Front

What are the 2 types of endonucleases?

Back

Preview of the front of card 4

Card 5

Front

What is another technique that can be used to isolate the desired gene?

Back

Preview of the front of card 5
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