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Techniques have been developed to isolate genes, clone them and transfer them into microorganisms.
These microorganisms are then grown for the continuous production of a desired protein.
The DNA of two different organisms that have been combined in this way is called recombinant DNA.
The resulting organism is known as…

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Using Restriction Endonuclease

All organisms use defensive measures against invaders.
Bacteria are frequently invaded by viruses that inject their DNA into them in order to take over the cell.
Some bacteria defend themselves by producing enzymes that cut up the viral DNA.
These enzymes are called restriction endonucleases.

There are…

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DNA Ligase

This enzyme repairs broken DNA by joining two
nucleotides in a DNA strand.
Ligase is therefore a bit like DNA polymerase.
It is commonly used in genetic engineering to do the
reverse of a restriction enzyme, i.e. to join together
complementary restriction fragments.
Two restriction fragments can anneal…

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Introduction of DNA into host cells

Once the DNA has been incorporated into at least some of the plasmids, they must then be reintroduced
into bacterial cells.
This process is called transformation and involves the plasmids and bacterial cells being mixed together
in a medium containing calcium ions.
The calcium…

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There are a number of different ways of using gene markers to identify whether a gene has been taken
up by bacterial cells.
They all involve using a second, separate gene on the plasmid.

This second gene is easily identifiable:
· It may be resistant to an antibiotic
· It…

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Polymerase Chain Reaction

The polymerase chain reaction is a method of copying fragments of DNA.

The process requires the following:

The DNA fragment to be copied
DNA polymerase an enzyme capable of joining nucleotides together
it is obtained from bacteria in hot springs and is tolerant to high
temperatures an…

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In vivo In Vitro

Particularly useful where we want to Extremely rapid
introduce a gene into another organism Particularly valuable where only a minute
amount of DNA is available

Involves almost no risk of contamination Does not require living cells
This is because a gene that has been cut All…

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Genetic engineering is known as recombinant DNA technology.
The genetic makeup of organisms can now be altered by transferring genes between the individuals of
the same species of between organisms of different species.
Organisms that have had their DNA altered by genetic engineering are called transformed organisms.
These organisms have…

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Genetically Modified Plants

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Genetically Modified Animals

An example of genetically modified animals is the transfer of genes from an animal that has natural
resistance to a disease into a totally different animal.
This second animal is then made resistant to that disease.
In this way, domesticated animals can be more economic to rear…


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