Download Using restriction enzymes, foreign genes can be added to an

Restriction Enzymes: How is DNA Manipulated?
Using restriction enzymes, foreign genes can be added to an existing organism (or an
embryo). This organism has been genetically modified.
Adding new genes can create plants that are more resistant to pests or be more tolerant to
weather patterns, such as drought. This technology can also be used to mass produce chemicals,
such as human growth hormone, by inserting that gene into bacteria.
In order to combine the DNA, a chemical called a restriction enzyme is used to cut the DNA
into fragments, exposing the gene of interest. On either side of the gene is an area of DNA
called the “sticky end.” The bases of the sticky end are ready to be paired to the new DNA
following the base-pair rule. That gene is then spliced to the other organism’s DNA using
another enzyme called ligase, the joining procedure is called ligation.
Sometimes scientists want a gene removed without the sticky ends, so that it will not bind to
other parts of DNA. These fragments are said to have “blunt ends”.
*Recombinant DNA is often abbreviated as rDNA to denote that it has foreign genes (DNA)
inserted into its genome.
This image shows a restriction enzyme called EcoRI being used to cleave a section of
DNA. Different restriction enzyme will cleave DNA at different sequence points, called
recognition sites, so scientists must isolate the right enzyme for the job – one that cuts around
the desired gene.
You will often see restriction enzyme sites written like this: G / A A T T C.
How is DNA Manipulated?
1. Explain the following terms and their role in recombinant DNA technology
a) Restriction enzyme
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b) Recognition site
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c) Sticky end
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d) Ligation
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Here are some restriction enzymes and their sites.
BAMHI
HindIII
EcoRI
SalI
G/GATCC
PstI
A/AGCTT
G/AATTC
HhaI
GCG/C
HpaII
C/CGG
The following enzymes produce blunt, not sticky
ends.
TGG/CCA
BalI
ACC/GGT
GTC/GAC
HindII
CAG/CTG
G/TCGAC
CTGCA/G
2. On each of the sequences below, determine which restriction enzyme could be used to splice
the DNA and indicate where the cut will be made and the enzyme used.
5' T T T G A A T T C A G A T 3'
1. 3' A A A C T T A A G T C T A 5'
5' G T G G G A T C C C T T A 3'
2.
3' C A C C C T A G G G A A T 5'
Enzyme:
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Enzyme:
________________
5' A C G C C T C C G G A G A 3'
3' T G C G G A G G C C T C T 5'
5' T T A A G C T T A A G A A G C T T 3'
4.
3' A A T T C G A A T T C T T C G A A 5'
5' A A G C G C G T C G A C T T A T A 3'
5.
3' T T C G C G C A G C T G A A T A T 5'
5' A A T G G C G G A T C C A A A C G C G A A T T C G G G 3'
6.
3' T T A C C G C C T A G G T T T G C G C T T A A G C C C 5'
3.
Enzyme:
_______________
Enzyme:
_______________
Enzyme:
_______________
Enzyme:
_______________
3. Create a restriction enzyme that will remove the gene of interst. Give it a name too!