Transcript Applications of Genetic Engineering

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We have mentioned previously that it is
possible to insert DNA from one organism to
another
◦ These are known as transgenic organisms
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These have many uses
◦ Production of human proteins (such as insulin) in
bacteria
◦ Modified crops to increase yield
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But the more notable, and controversial,
transgenic organisms would be clones
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Scientists have developed methods to make
genetic copies (clones) of entire organisms
The problem came from the fact that cells will
differentiate during the embryonic stage, and
could not revert back
The answer came when it was discovered that
cells in G0 could be forced into a totipotent
stage
This was first successfully performed in 1996
with the creation of Dolly
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Dolly was created by removing a mammary
cell from an adult sheep
The cell was forced into G0, and its nucleus
removed
An egg cell from another sheep was removed,
and its nucleus was removed
The nucleus from Dolly’s donor was inserted,
and the egg was implanted into a womb
The lamb that was born (Dolly) was the
genetic copy of the donor
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Dolly was euthanized when she was 6
◦ Most sheep live 10-12 years
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It was speculated that her genetic age was
older than her birth age
Her telomeres were artificially short, since
she was cloned from an older sheep
This raised questions about the viability of
cloned organisms
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Blood and tissue samples are often left at
particularly violent crime scenes
Scientists used to use blood type as a method
of indentifying a defendant
◦ However, this only proves if a person is innocent
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DNA fingerprinting (now called profiling) can
indentify the guilty individual with a much
higher certainty
A few different methods have been used
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Many of the technologies we have discussed
are used to directly assist humans
In particular, DNA fingerprinting has become
quite useful
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Restriction fragment length polymorphism
Restriction enzymes are added to suspect’s
DNA, and samples of DNA at crime scene
The length of introns is variable in a
population
When a gel is ran, the two samples are
compared
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More recently, variation in the lengths of
satellite DNA have been used
These are repeats of the same 1-10
nucleotides, and are highly variable in
humans
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Restriction enzymes are still used
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Started in 1990, projected completion by
2005
Essentially completed in 2000, officially
announced in 2003
First found sequence of small sequences far
apart
◦ Used these as makers
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Cut the genome up into many smaller
segments, and sequenced these separately
Computer analyzed to find areas of overlap
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Aligned these, with markers, to get complete
version
Called this shotgun sequencing
Next up was to look for genes
Scan for promoting regions
Then, have to differentiate between intron
regions and exon regions
Indentifying the genes is the first step in gene
therapy
Is the proper sequence is known, a strand can
be engineered into a virus, and inserted into
a patient