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new horizons in medicine
Since genetic engineering (also known as The basic steps in the genetic engineering of a bacterium Gene therapy
The required gene is EITHER cut from the DNA of an organism
recombinant DNA technology or genetic
using enzymes called restriction endonucleases which Gene therapy is still in it’s very early stages. It involves
modification) was first developed in the 1970s leave the gene with overlapping sections called sticky ends... ...OR ...synthesised specifically modifying human DNA either to repair it or to replace
a faulty gene. The idea of gene therapy is
scientists have discovered more and more to overcome the effects of a mutation which causes
ways in which this new technology can be Required gene a genetic disease. Cystic fibrosis is the best known
sticky ends disease where gene therapy has been tried.
used in human medicine. The same basic There have been no long term successes – yet!
technique is used in modifying the genetic Bacterial
Gene with plasmid
material of bacteria, plants and animals.
Pharming A vector molecule (often a bacterial
plasmid, the small circular strand of DNA
Microorganisms, animals and plants found in bacteria) is opened up, also Marker
can be genetically modified to gene
produce medically useful products.
using restriction enzymes and leaving
These transgenic organisms are
Some vaccines are very dangerous to make using
already used regularly to produce
conventional methods. Genetically engineered
substances such as human insulin,
microbes can be used to produce the antigens
human growth hormone and blood
needed in a safe and controllable way. The use of
clotting factors for haemophiliacs.
genetically modified yeast cells to produce a
vaccine against the hepatitis B virus has been a
The new gene is annealed (joined major success story.
into the plasmid using the sticky ends)
and sealed in place using another
enzyme known as DNA ligase. ett
Genetic engineering is opening up
opportunities to produce very Bacterium Xenotransplantation
specific and sensitive diagnostic tests
for many diseases, using engineered Plasmid with The DNA of pigs has been modified using
recombinant DNA technology so their cells develop
proteins. This new technology is also The recombinant plasmid is engineered gene
without certain genes which trigger the human
opening up novel ways of delivering inserted into a bacterial cell in a
immune response. The hope is that these genetically
medicines to specific targets. process known as transformation. Bacterial
modified organs might be accepted by a human
It is then replicated whenever the
DNA recipient. In time pigs may even be given genes
bacterial cell replicates, and brings
which code for human antigens – but there are
n tre about the manufacture of a new
Lib netic many ethical and safety questions still to be
ho l G
e P na
We ssex answered in this area of genetic engineering.
Ph yal V