What 4 steps are necessary in genetic engineering?
The required gene is obtained. A copy of the gene placed in a vector. Vector carries the gene to the recipient cell and recipient expresses the gene through protein synthesis.
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What does genetic engineering describe?
A number of different processes for obtaining a specific gene and placing the gene in another organism.
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Define transgenic
Organism that contains genetic material from an unrelated organism.
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What methods can be used to obtain the gene to be engineered? (3)
mRNA produced from transcription of the gene obtained from cells where the gene is expressed. mRNA used as a template to copy the gene. Gene synthesised using an automated polynucleotide sequencer. DNA probe locates the gene
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How can the gene be placed in a vector? (2)
Sealed into bacterial plasmid using enzyme DNA ligase. Sealed into virus genomes.
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How does the gene get into the recipient cell? (5)
Electropolation, microinjection, viral transfer, Ti plasmids, liposomes.
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Describe electropolation
A high-voltage pulse is applied to disrupt the membrane.
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What is microinjection?
DNA injected using a fine micropipette into the host cell nucleus.
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Describe viral transfer
Vector is a virus, inserts DNA directly.
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Describe Ti plasmids
Used as plasmids - can be inserted into soil bacterium. Plants can be infected with bacterium which inserts plasmid DNA into plant's genome.
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How can liposomes be used to get the gene into the recipient cell?
DNA wrapped in lipid molecules. These are fat-soluble and can cross the lipid membrane by diffusion.
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What do recombinant DNA techniques often involve?
Involve the cutting and sticking together of DNA strands.
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What are restriction enzymes used for?
Used to cut through DNA at specific points.
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What a restriction site?
A specific base sequence on DNA where a particular restriction endonuclease will cut only where this sequence occurs.
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When is a sticky end formed?
When DNA is cut using a restriction enzyme. Short run of exposed, unpaired bases at the end of the cut section.
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What is the role of DNA ligase?
Used to catalyse a condensation reaction which joins the phosphate-sugar backbones of the DNA double helix together.
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What must happen to join DNA fragments from different sources?
Both need to have been cut with the same restriction enzyme so the sticky ends are complementary.
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What is recombinant DNA?
A section of DNA, often in the form of a plasmid, which is formed by joining DNA sections from 2 different sources.
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Other cards in this set
Card 2
Front
What does genetic engineering describe?
Back
A number of different processes for obtaining a specific gene and placing the gene in another organism.
Card 3
Front
Define transgenic
Back
Card 4
Front
What methods can be used to obtain the gene to be engineered? (3)
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