2. Uses of genetic modification
Genetically modified crops – to grow in climates which are inhospitable
Tomatoes will not soften as easily
Wheat resistant to herbicides
Rice with added vitamin A
3. Genetically modified mice – mice can be genetically modified to develop human
types of diseases such as Asthma and cancers which research scientists can then
test on to see which drugs work
These are coloured with GFP Green Jelly fish proteins used as genetic marker
4. Gene therapy - This is where scientists replace defective genes
with active genes cloned from healthy individuals.
There are two types of gene therapy although this sort of therapy is
in it’s infancy for humans.
Germ line therapy – which is currently banned in most countries
the more acceptable
Somatic cell therapy which isn’t very successful however a young
man had his sight partially restored in 2008 using this method.
5.
6.
7.
8.
9. Tranformed Goats and Genetically modified sheep - Sheep and goats can have specific
genes for various proteins added alongside the milk promoter gene in a plasmid when still
zygotes.
These proteins will be expressed in the mammary glands of the animals.
The protein can then be extracted from the milk and used. Applications include: -
Medicinal
anti-thrombin
anti-trypsin
10. The genes for spiders web proteins a very strong natural fibre can also be inserted into
mammary gland of sheep and goats and will be expressed with the animals milk.
Spiders can’t be farmed for their silk proteins as they are cannibals.
But their silk can be used to create.
Bullet-proof clothing as spider silk is tougher than Kevlar
Wear-resistant lightweight clothing
Ropes, nets, seat belts, parachutes
Rust-free panels on motor vehicles or boats
Biodegradable bottles
Bandages, surgical thread
Artificial tendons or ligaments, supports for weak blood vessels
http://www.biologymad.com/ [ accesssed 05/03/2012] Toole and Toole, 2008
11. So lets look at genetic modification of sheep so that they produce various
proteins along with their milk.
First of we’d need a plasmid.
foreign genes can quite easily be incorporated into them using restriction enzymes
and DNA ligase.
12. This plasmid contains a replication
origin, several recognition sequences
for different restriction enzymes (with
names like PstI and EcoRI), and two
marker genes, which confer resistance
to different antibiotics (ampicillin and
tetracycline).
Into this you could add the gene for
Green Fluorescent Jelly fish protein
also.
Then you’d add the gene for milk
promotion and designer gene which you
were adding to code for the particular
protein you wanted out of the milk
It could be a protein for inhalation to
stop lungs destroying themselves
Or a protein to stop blood clotting
Or it could be for spiders silk.
13.
14. The sheep is given FSH
hormones to increase ova
maturation. These are harvested
and fertilised in vitro
The ova are fertilised in the
laboratory
15. A plasmid is prepared containing the designer gene
the promoter sequence for b-lactoglobulin and a
green, fluorescent, jelly fish. Hundreds of copies of
this plasmid are microinjected into the nucleus of
the fertilised zygotes.
Only a few of the zygotes will be transformed, but at
this stage you can’t tell which.
16. The genes we introduce are coupled to a promoter for the
milk protein β-lactoglubulin.
Since this promoter is only activated in mammary gland
cells, the inserted genes will only be expressed in
mammary gland cells, and so will be secreted into the
sheep's milk. This makes it very easy to harvest and purify
without harming the sheep.
18. The 16-cell embryos are implanted into
the uterus of surrogate mother ewes.
Only a few implantations result in a
successful pregnancy.
Some of the lambs will be green this will
determine which ones have been
transformed and which lambs are
unchanged.
About 1 in 20 eggs are successful.
19. Collect milk from the transgenic
sheep for the rest of their lives.
Also breed from them in order to
build up a herd of transgenic
sheep.
Purify the protein for example AAT, is
worth about
£50 000 per mg
20. The first transgenic sheep to produce AAT was
called Tracy, and she was produced by PPL
Pharmaceuticals in Edinburgh in 1993. :
21. Ethical and Moral Considerations
Many types of genetic engineering are considered to be socially unacceptable as it
can lead to Eugenics and potentially dangerous as man made genes added to the
environment could drastically change the ecology of the country.
For example a crop genetically engineered to withstand a certain herbicide which
was going to increase the yield. May pass that gene to a weed. Then the weed would
become resistant to the herbicide so the crop and the weed would then once more
be competing for nutrients and light.
Then we’d have to come up with another type of herbicide which was compatible
with the environment and the new crop we are growing. This would be a very
expensive and take time to trial as we would have to be careful that we were not
damaging the environment.
For these reasons GM Crops are banned in the UK
22. References
Toole and Toole AQA Biology Study Guide,
Nelson Thornes. 2008
Biology Mad Website Accessed March 1st 2012
