Genetic engineeringgenetic modification

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23 Οκτ 2013 (πριν από 3 χρόνια και 5 μήνες)

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Genetic engineering
, also called
genetic modification
, is the direct human
manipulation of an organism's
genome

using modern DNA technology. It involves
the introduction of
foreign DNA

or
synthetic genes

into the organism of interest.
The introduc
tion of new DNA does not require the use of classical
genetic

methods, however traditional
breeding

methods are
typically used for the
propagation of recombinant organisms.

An organism that is generated through the introduction of
recombinant DNA

is
considered to be a
genetically modified organism
. The first organisms genetically
engineered were bacteria in 1973 and then mice in 1974.
Insulin
-
producing
bacteria were commercialized in 1982 and genetically modified food has been sold
since 1994.

The most common form of genetic engineering involves the insertion of new
genetic material at an unspecified location in th
e host genome. This is
accomplished by isolating and copying the genetic material of interest using
molecular cloning

methods to generate a DNA sequence containing the re
quired
genetic elements for
expression
, and then inserting this construct into the host
organism. Other forms of genetic engineering include
gene targeting

and knocking
out specific genes via engineered
nucleases

such as
zinc finger nucleases

or
engineered
homing endonucleases
.

Genetic engineering techniques have been applied in numerous fields inc
luding
research, biotechnology, and medicine. Medicines such as insulin and human
growth hormone are now produced in bacteria, experimental mice such as the
oncomouse

and the
knockout mouse

are being used for research purposes and
insect resistant and/or herbicide tolerant crops have been commercialized.
Genetically engineered plants and animals capable of producing biotechnology
drugs more cheaply than current methods (called
pharming
) are also being
developed and in 2009 the FDA approved the sale of the pharmaceutical protein
antithrombin

produced in the milk of genetically engineered
goats
.

Genetic engineering alters the genetic makeup of an organism using techniques
that introduce
heritable

material prepared outside the organism either directly into
the host or into a cell that is then
fused

or
hybridized

with the host.
[1]

This involves
using
recombinant nucleic acid

(
DNA

or
RNA
) techniques to form new
combinations of heritable genetic material followed by t
he incorporation of that
material either indirectly through a
vector

system or directly through
micro
-
injection
, macro
-
injection and
micro
-
encapsulation

techniques. Genetic
engineering does not include traditional
animal

and
plant breeding
,
in vitro
fertilisation
, induction of
polyploidy
,
mutagenesis

and cell fusion techniques that
do not use recombinant nucleic acids or a genetically modified organism in the
process.
[1]

Cloning

and
stem cell

research, although not considered genetic
engineering,
[2]

are

closely related and genetic engineering can be used within
them.
[3]

Synthetic biology

i
s an emerging discipline that takes genetic engineering
a step further by introducing artificially synthesized genetic material from raw
materials into an organism.
[4]

If gen
etic material from another species is added to the host, the resulting organism
is called
transgenic
. If genetic material from the same species or a species that can
naturally breed wi
th the host is used the resulting organism is called
cisgenic
.
[5]

Genetic engineering can also be used to
remove genetic material from the target
organism, creating a
gene knockout

organism.
[6]

In Europ
e genetic modification is
synonymous

with genetic engineering while within the United States of America it
can also refer to conventional breeding methods.
[7]

Within the scientific
community, the term
genetic engineering

is not commonly used; more specific
terms such as
transgenic

are preferred