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Agriculture
Transgenic Plants
Production of Bovine Somatotrophin
Revision
 How is genetic engineering of
organisms carried out (think back to
SG and Higher)?
 What is needed?
 What is substances are produced
through genetic engineering?
 What else do we know?
Transgenic Plants
 A transgenic organism is an organism
that is carrying genetic material of
another organism in its genome.
 Producing a transgenic organism
requires:
 A vector used to insert the required DNA
into a plant
 A way of ensuring the gene is carried in all
cells
Vectors
 A vector is an agent used to transfer
DNA from one organism to another
 Agrobacterium (tumerfaciens) is a
commonly used vector
 Agrobacterium is a soil bacteria
 It contains a plasmid (known as Ti)
which it can insert into plant DNA
causing a tumour (crown gall disease)
Vectors cont…
Procedure for creating a transgenic
plant using a Ti-plasmid
 Ti disease gene is disabled
 Eg. By removing it with restriction
enzymes
 A target gene containing desired
characteristics is identified
 A target gene is removed from source
DNA using a restriction enzyme
 The plasmid is then cut using the
same restriction enzyme
Procedure for creating a transgenic
plant using Ti cont…
 The foreign DNA (target gene) is then
added to the plasmid and sealed
using DNA ligase
 The modified plasmid is returned to
the Agrobacterium
 (Note the plasmid also has a method
for identification e.g antibiotic
resistance – later in the process this
is used to identify the cells that have
the plasmid)
Procedure for creating a transgenic
plant using Ti cont…
 Plant cell protoplasts are prepared
 The protoplasts are incubated with
the bacterium containing the modified
plasmid
 Grown in a selective medium that
allows only the growth of cells
containing the plasmid (and selected
gene)
 E.g the medium may contain an antibiotic
Example 1 – insect resistance
 The bacteria Bacillus thuringiensis
produces proteins (known as BT
toxins) that have been used for
insecticides
 The toxin is isolated from the bacteria
genome and inserted into Ti plasmid
of agrobacterium
 The resulting plant kills insects that
eat it
Example 1 – insect resistance
 Potato, cotton and soybean are all
plants were this technique is used
 Benefits
 Only insects eating the plant are killed
 Reduces the use of pesticides
 The entire plant has protection (not just
the leaves and stem, as would be the
case if it was sprayed)
Example 2 – Tomato plants
 Tomato ripening is naturally accompanied
by softening due to an enzyme – PG
(polygalacturonase)
 Fruit an usually picked while still green and
ripened artificially using ethene gas
 By modifying the PG gene, fruit could be
left to ripen longer without softening
 Fresher, riper tomatoes could be delivered
to supermarkets
Bovine Somatotrophin (BST)
production
 Bovine somatotrophin is a growth
hormone that can be used to increase
growth (mainly muscle and bone) and
milk production in cattle
 The gene is isolated from cattle cells
using restriction enzymes
 A restriction enzyme is also used to
open a plasmid from an E. coli
bacteria
Bovine Somatotrophin (BST)
production
 The BST gene is inserted into the
plasmid using DNA ligase
 The E.coli bacteria containing the
plasmid are then cultured
 The gene is expressed (i.e.
transcribed and translated into
protein form) during bacterial growth
 The protein is then purified and
prepared for administration to cattle
Use of BST
 BST is either administered by
injection or the protein is included in
cattle feed
 Results in a 10% increase in milk
production
Disadvantages / concerns
 Can increase mastitis in cows
 Lameness later in life – due to
enlarged udders
 BST causes a lack of fat deposits
(more of the glucose etc.. is used)
therefore hypothermia can develop
 BST found in milk – supposedly safe
as it will be broken down in our
stomachs
Learning Activities
Monograph pg 90 – 94
DART pg 88 – 93
Scholar
Genetically Modified Plants worksheet
Make flow diagrams / posters of the process of
 Creating transgenic plants
 BST production
 Assignment Questions – 2001 Q12, 2005 Section B Q
8
 Look at websites
 http://www.food.gov.uk/gmfoods/gmtt/gmplantshow
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Moral and Ethical Issues related to
transgenic organisms
 Moral and Ethical codes attempt to
establish acceptable human behaviour for
the benefit of all society ‘DART’
 Transgenic organisms
 What rights do they have?
 Farmers
 What might there opinions towards transgenic
be? How might differing views on accompanying
farms be dealt with?
Moral and Ethical Issues related to
transgenic organisms
 Consumers
 What are the pros and cons?
 What are the facts vs media hype?
 The Environment
 Benefits vs problems
 Biotechnology Industry
 Motives vs issues
Formal Debate
 This house supports the creation and
use of transgenic organisms
THE END OF UNIT ONE
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(Except for the NAB)