Download DNA Recombinations

Hypothetical Situation
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Genes that produce chlorophyll in plants are
inserted into the chromosomes of cattle.
What are some of the advantages of this
procedure?
The result would be an animal that is
capable of making its own food.
Can you think of the potential benefits of this
kind of research?
DNA Recombination
a.k.a. Gene Splicing
What is it?
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Recombinant DNA refers to a new
combination of DNA molecules that are not
found together naturally.
Produced by joining DNA molecules from
different biological sources.
The hybrid DNA is then inserted into a host
cell, often a bacterium, for replication.
Click
Tools Needed
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Restriction enzymes (biological
scissors) "cut" DNA at a specific
location.
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DNA ligase (DNA glue) is used to
"glue" two sections of DNA
together.
Plasmids…
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Recombinant DNA is often
created using a plasmid.
Plasmids are DNA structures
in bacteria
http://faculty.abe.ufl.edu/~chyn/age2062/lect/lect_09/FG10_001.GIF
http://www.microbeworld.org/microbes/virus_bacterium.aspx
… or Viruses
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The DNA in a virus can also be used for
creating recombinant DNA
The virus can enter another cell and have its
genetic code replicated by that cell
http://www.microbeworld.org/microbes/virus_bacterium.aspx
Products of Recombinant DNA
Technology
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Some examples of recombinant DNA
products include insulin and growth hormone.
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Vaccines can also be produced using
recombinant DNA technology.
Step by Step…
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Let’s look at the process of DNA
recombination…
Step 1: A restriction enzyme is used
to cut a specific DNA strand from the
DNA of a cell
Step 2: The cut DNA strand is
inserted into a virus.
Step 3: The virus is inserted
into a cell
Step 4: The cell passes the foreign
gene on to all daughter cells
A Close-up View of DNA insertion
into a plasmid
Areas Where Recombinant
DNA will have an Impact
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Better Crops (drought & heat resistance)
Recombinant Vaccines (ie. Hepatitis B)
Prevention and cure of sickle cell anemia
Prevention and cure of cystic fibrosis
Production of clotting factors
Production of insulin
Plants that produce their own insecticides
Gene therapy
Connections to the World
Around Us
http://static.howstuffworks.com/gif/photocopier-xerox.jpg
Activity:
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Make your own recombinant DNA!!
Impact of Recombinant DNA
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Improved Medicines
Improved Livestock (resistance to
disease)
Improved Crops (resistance to
disease, higher yields)
Prevention of Genetic Diseases
Lowering the cost of medicines
(i.e. Insulin)
Safer Medicines (i.e. Insulin)
Treatment for pre-existing
conditions (i.e. Cancer)
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Safety concerns (viruses
developing antibiotic resistance)
Environmental concerns
(developing resistance to fungi)
Ethical dilemmas over human
treatment (i.e. are we playing
God?)
Potential for Experimental abuse
(doctors using patients as test
subjects)
Germline treatment going from
treating diseases to a method for
picking the traits you want in a
child (i.e. specifying hair and eye
color)
Cutting DNA Strands
The major tools of recombinant DNA
technology are bacterial enzymes called
restriction enzymes. Each enzyme
recognizes a short, specific nucleotide
sequence in DNA molecules, and cuts
the backbones of the molecules at that
sequence. The result is a set of doublestranded DNA fragments with singlestranded ends, called "sticky ends."
Sticky ends are not really sticky;
however, the bases on the sticky ends
form base pairs with the complementary
bases on other DNA molecules. Thus,
the sticky ends of DNA fragments can
be used to join DNA pieces originating
from different sources.
http://www.accessexcellence.org/RC/AB/WYW/wkbooks/SFTS/activity6.html
Creating Recombinant
Plasmids
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http://www.accessexcellence.org/RC/AB/WYW/wkbooks/SFTS/activity6.html
In order to be useful, the
recombinant DNA
molecules have to be made
to replicate and function
genetically within a cell.
One method for doing this
is to use plasmid DNA from
bacteria. Small DNA
fragments can be inserted
into the plasmids, which
are then introduced into
bacterial cells. As the
bacteria reproduce, so do
the recombinant plasmids.
The result is a bacterial
colony in which the foreign
gene has been cloned.