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parsimoniouswoowooBiotechnology

Dec 11, 2012 (4 years and 10 months ago)

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Gene Technology

Molecular biologists can manipulate DNA to clone genes
:

The DNA Manipulator's Toolbox


Restriction endonucleases

are able to cleave DNA at speci
fic restriction sites.


DNA ligase

joins DNA fragments
by catalyzing the formation of phosphodiester
bonds b
etween DNA nucleotides.


Host/Vector Systems


The ability to propagate DNA in a host cell requires a vector that can enter and
replicate in the host. The two most commonly used vectors are plasmids and

phages.

• Using these vectors, the gene or genes of interest are introduced into the target
organisms, where they infect cells and replicate
the altered vector DNA.


Using Vectors to Transfer Genes

• Viruses and artificial chromosomes can

also be used a
s vectors to insert foreign
DNA into host cells, creating recombinant DNA a
nd recombinant genomes.


DNA Libraries

• A DNA library is a collection of DNA fragments from a specific source in a form
that can b
e propagated in a host.


• A genomic library is
a representation of the enti
re genome in a vector.


Genetic engineering involves easily understood procedures
:

The Four Stages of a Genetic Engineering Experiment

• The four stages of a genetic engineering experiment are (1) cleaving the source
DNA, (2) p
roducing recombinant DNA, (3) cloning copies of the recombinants,
and (4) screening the cloned copies for t
he desired genes.

Working with Gene Clones

• One approach to making enough DNA to work with is to use DNA polymerase
to copy the gene of interest th
rough the
polymerase chain reaction

(
PCR
).


• The three steps in PCR are denaturation, primer annealing
, and primer
extension.


• After 20 cycles, a single fragment produces more than one million copies of
the
target sequence.


• In the
Southern Blotting

process, DNA is cleaved into restriction fragments,
and the fragments are then separated by gel electrophoresis. Fragments that
contain the gene of interest can then be identified when a radioactively labeled
probe is washed over paper that contains a co
p
y of the gel's pattern.



Restriction fragment length polymorphisms

(
RFLP
)

analysis and DNA
fingerprinting are both used to identify individuals and specific
unknown gene
sequences.



Biotechnology is producing a scientific revolution:

Medical Applicatio
ns

• Pharmaceuticals, gene therapy, and piggyback vaccines are all medical
applications that have been developed from biotec
hnology advances.

Agricultural Applications

• Increased nitrogen fixation, herbicide resistance, insect resistance, and dietary
defi
ciencies are all agricultural problems that are currently being addressed via
gene technology and tr
ansgenic species.

Risk and Regulation


Genetic engineering

has the potential to create great medical and agricultural
advances, although many people are c
oncerned with possible risks of genetic
engineering, especially those associated wi
th transgenic species.

• In short, the potential benefits of genetic engineering appear to outwei
gh the
potential risks.