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Genetic engineering
is an umbrella term which can cover a wide range of ways of changing
the genetic material - the DNA code - in a living organism. This
code contains all the information, stored in a long chain chemical
molecule, which determines the nature of the organism - whether
it is an amoeba ,
a pine tree, a robin,
an octopus, a cow or a human being - and which characterises the
particular individual. Apart from identical twins, your detailed
genetic make-up is unique to you. Individual genes are particular
sections of this chain, spaced out along it, which determine the
characteristics and functions of our body. Defects of individual
genes can cause a malfunction in the metabolism of the body, and
are the roots of many "genetic" diseases.
Our understanding
of our genetic makeup is being greatly expanded by a systemmatic
mapping process known as the Human Genome Project, carried out
internationally with enormous commercial and government funding.
Smaller projects are also drawing the genetic map of pigs, chickens
and some other organisms. As this work proceeds, individual genes
are being identified for various functions and especially for
medical conditions. Sometimes it appears that a single gene is
responsible, for example in cystic fibrosis, but most conditions
seem to be caused by more complex sets of factors, both genetic
and environmental. We should make an important distinction between
a gene which causes a condition outright, and one that gives one
a susceptibilty to it, but which requires other factors to be
present as well for the condition to develop.
The ability
to detect such genes now means we can use the tests for screening,
especially pre-natally. This raises some important ethical questions,
as we shall see. Screeing for various diseases is not, strictly
speaking, the same thing as manipulating or "engineering" them.
Some people feel "engineering" is an inappropriate term, with
connotations of cold mechanics rather than living things, but
it does reflect that manipulating genes has in some cases become
a relatively common laboratory technique. We should also put it
in context, that genetic engineering has been performed for centuries
in animals and plants by selective breeding. This enhances particular
genetic traits based on outward appearance, by choosing, for example,
which boars to mate which sows to develop, over many generations,
leaner pig meat.
Leslie
Gornstein
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