Genetic Engineering
2
1.1 What is genetic engineering?
• A technique in biotechnology
• Used to transfer genes from one
organism to another (need not be
the same species)
• Any organism that acquires a
foreign gene is called a
transgenic organism
How is genetic
engineering
useful to man?
2.1 Transgenic casein cows
Nine cloned cows in New Zealand are producing
milk with an unusually high amount of protein.
The herd has extra copies of genes for two
forms of casein, the major protein in milk and the
main component of curd.
2.2 Transgenic carnations
Wilt-proof flowers, last for three weeks
after cutting. Normal flowers wilt after
three days
2.3 Transgenic salmon
Shortened production cycles, and
eleven times heavier than nontransgenic salmon
2.4 Transgenic pea plants
Weevil
proof peas
2.5 Cloning
2.6 Genetic engineering in
medicine
• Many inherited diseases are caused when
the body cannot make a particular protein
• Haemophilia.
– Haemophiliacs cannot make the protein Factor 8
which helps clotting.
• Diabetes
– Diabetics cannot make the protein insulin.
• Genetic engineering can be used to make
large amounts of these proteins.
3.1 How does genetic engineering
work?
•
•
•
•
•
•
Identifying the specific gene
Isolating the gene
Inserting the gene into a vector
Inserting the vector into a host cell
Multiplying the host cell
Synthesizing the product by the host
cell
• Separating the product from the host
cell
• Purifying the product
3.2 Important terms in genetic
engineering
• Restriction enzymes
– To cut DNA at specific points, making small
fragments
• DNA ligase
– To join DNA fragments together
• Vectors
– To carry DNA into cells and ensure
replication
• Plasmids
– Common kind of vector
• Transgenic bacteria
3.3 Activity : DNA Recombination
• Simulate how genes are
removed from one cell and
inserted into another
How EcoRI works?
Genetic Engineering
The process
1
2
3
Isolate the desired gene
Insert the gene into the vector DNA
Insert the recombinant DNA into bacteria
Genetic Engineering
Producing human insulin
Background:
Type 1 diabetes is caused by the inability of the
islets of Langerhans to produce sufficient insulin.
• Mass production of human insulin for type
1 diabetes patients was made possible
through the use of genetic engineering.
• The human insulin gene is transferred to
bacterial cells that are able to express the
gene. The product (insulin) can then be
harvested.
• https://www.youtube.com/watch?v=AEINu
CL-5wc
Genetic Engineering
insulin gene
1 • Obtain the human chromosome
containing the insulin gene.
How the human insulin
gene is inserted into
bacterial DNA
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12 April 2015
17
Genetic Engineering
insulin gene
cut by restriction
enzyme
sticky end
fragment of DNA containing
the insulin gene
1 • Obtain the human chromosome
containing the insulin gene.
• Cut the gene using a restriction
enzyme. This enzyme cuts the
two ends of the gene to produce
‘sticky ends’.
How the human insulin
gene is inserted into
bacterial DNA
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
12 April 2015
18
Genetic Engineering
insulin gene
cut by restriction
enzyme
sticky end
fragment of DNA containing
the insulin gene
1 • Obtain the human chromosome
containing the insulin gene.
• Cut the gene using a restriction
enzyme. This enzyme cuts the
two ends of the gene to produce
‘sticky ends’.
• Each ‘sticky end’ is a single
strand sequence of DNA bases.
These bases can pair with
complementary bases to form a
double strand.
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
How the human insulin
gene is inserted into
bacterial DNA
12 April 2015
19
Genetic Engineering
insulin gene
plasmid
cut by restriction
enzyme
sticky end
fragment of DNA containing
the insulin gene
2 • Obtain a plasmid from a
bacterium.
How the human insulin
gene is inserted into
bacterial DNA
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
12 April 2015
20
Genetic Engineering
insulin gene
plasmid
sticky ends
cut by restriction
enzyme
sticky end
fragment of DNA containing
the insulin gene
cut by same
restriction enzyme
2 • Obtain a plasmid from a
bacterium.
• Cut the plasmid with the same
restriction enzyme. This produces
complementary sticky ends.
How the human insulin
gene is inserted into
bacterial DNA
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
12 April 2015
21
Genetic Engineering
insulin gene
plasmid
sticky ends
cut by restriction
enzyme
sticky end
fragment of DNA containing
the insulin gene
cut by same
restriction enzyme
3 • Mix the plasmid with the DNA
fragment containing the insulin
gene.
How the human insulin
gene is inserted into
bacterial DNA
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
12 April 2015
22
Genetic Engineering
plasmid
insulin gene
sticky ends
cut by restriction
enzyme
sticky end
fragment of DNA containing
the insulin gene
3 • Mix the plasmid with the DNA
fragment containing the insulin
gene.
cut by same
restriction enzyme
DNA
ligase
insulin gene
inserted into
plasmid
• Add the enzyme DNA ligase to
join the insulin gene to the
plasmid.
How the human insulin
gene is inserted into
bacterial DNA
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
12 April 2015
23
Genetic Engineering
plasmid
insulin gene
sticky ends
cut by restriction
enzyme
sticky end
fragment of DNA containing
the insulin gene
4 • Mix the plasmid with E. coli
bacteria.
cut by same
restriction enzyme
DNA
ligase
insulin gene
inserted into
plasmid
bacterial DNA
E. coli
How the human insulin
gene is inserted into
bacterial DNA
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
12 April 2015
24
Genetic Engineering
plasmid
insulin gene
sticky ends
cut by restriction
enzyme
sticky end
fragment of DNA containing
the insulin gene
4 • Mix the plasmid with E. coli
bacteria.
• Apply temporary heat or electric
shock. This opens up pores in the
cell surface membrane of each
bacterium for the plasmid to
enter.
cut by same
restriction enzyme
DNA
ligase
insulin gene
inserted into
plasmid
bacterial DNA
E. coli
plasmid enters
the bacterium
plasmid
bacterial
DNA
How the human insulin
gene is inserted into
bacterial DNA
trangenic bacterium
Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd.
12 April 2015
25
Questions to ask
•
•
•
•
Why use bacterial plasmid?
Why use a bacterial cell?
Can we use a virus?
Can the DNA mutate?
• How viruses work?
• https://www.youtube.com/watch?
v=Rpj0emEGShQ
Genetic Engineering
Activity
Have you heard of the term ‘designer babies’?
Find out more about more about designer babies on
the Internet and prepare a presentation on it.
4.1 What are the advantages of
genetic engineering?
• Improves product quality and
quantity
• Generates cheaper products
• Products grown or extracted from
unconventional sources
2.2 Genetic engineering: Some
disadvantages
• Effect on the food web unknown
• Long-term side effects unknown
• Is it ethical?