Yerr baby!!!!

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Gene Therapy
Yerr baby!!!!
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The main advances in medicine

• Improved sanitation systems
• Surgery with anesthesia
• Vaccines and antibiotics
• And the fourth will be Gene Therapy

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What is gene therapy?

• The selective delivery of genes into a patients
  cells
• create missing proteins
• replace defective disease causing genes
• Over 4,000 conditions are caused by damage to a
  single gene, many others by several genes

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Gene therapy techinques
Ex-vivo outside the body adding blood cells
with new DNA to the blood stream but has a
limited time span Using bacteria like E.coli to
produce billions of copies of a human gene Using
viruses to carry the gene to specific cells in
the body
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What do you need?
A cutting enzyme called a
Restriction enzyme
It cuts foreign DNA that enter bacteria, e.g.
Eco. R1
A circular DNA molecule from a bacteria called a
Plasmid
The E. coli bacteria has dozens of different
plasmids
A section of the human DNA containing the gene
you need
An enzyme to join the bacterial DNA and human DNA
called
ligase
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Restriction Enzymes
Found in many bacteria A defense mechanism which
cuts foreign DNA The DNA is not cut randomly, but
at specific sequences called Recognition
sequences The restriction enzyme Eco.R1 found in
strain C, E. coli bacteria They dont make
straight cuts, but produce sticky ends These
sticky ends can rejoin by forming hydrogen bonds
and the sugar-phosphates rejoining with the help
of the enzyme ligase The DNA produced by
restriction enzymes cutting is called gDNA We
know of 200 different restriction enzymes
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Plasmids
The Plasmid pSC101 was isolated from E. coli. It
is useful for gene therapy because it has only
one sequence of GATTC in its entire
molecule Plasmids can be used to replicate DNA
segments of up to 4,000 base pairs in length For
longer length viruses must be used.
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Using Bacterial Plasmid
Cut the Bacterial Plasmid using restriction
enzyme called Eco R1
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• This produces a hole in the circular Plasmid DNA
• Eco. R1 only cuts at the sequence GAATTC
• This produces two identical ends

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Also treat human DNA with Eco.R1 and you get a
section of DNA containing the gene you want with
two complementary ends as well! Short sequence
of DNA with sticky ends approaches a Plasmid.
Plasmid
Human DNA
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Bacterial DNA
Human DNA
The newly completed piece of DNA is called
Recombinant DNA
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Using this Recombinant DNA
Gene cloning can now be used to produce millions
of copies
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A Plasmid with human DNA is put back into a E.
coli
The bacteria expresses the DNA. The bacteria then
divides to produce millions of copies bacteria
and human gene.
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A Plasmid cut by a restriction enzyme
Foreign DNA spliced into Plasmid by
Plasmid enters bacterial cell
Segment of DNA approaches
DNA ligase joins phosphates and sugars
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Using viruses
Viruses can be used to transfer large pieces of
human DNA to a location in the Human
body. Viruses are made up of a molecule of
nucleic acid and a protein coat. Their nucleic
acid codes for protein coats, replication,
enzymes to break-in and out of particular
cells. You remove the part of the nucleic acid
that does not code for the above functions and
add foreign DNA. The virus can then be put into
the blood stream and it will enter the cell it is
designed to attack and transfer its code into
that cell.
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• Some current uses trials of gene therapy
• Introduction of genes for new blood vessels for
  clogged arteries
• Introduction of genes into the blood stream that
  interferes with the replication of HIV
• Human growth hormone for Dwarfism
• Insulin production
• Glowing mice
• Replacing the cytoplasm in eggs to produce
  healthier eggs

Some current uses of gene therapy and later
cosmetic uses
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The future?
Injecting genes into the blood stream which are
then carried to the target cells by viral
carriers where they unload their genetic
material. This is then used by the body to
produce proteins that fight the disease. For the
next decade gene therapy will only be used on
somatic cells (only effect the patient and not
their offspring) You and bioethicists will have
to decide the future!