DNA BIOTECHNOLOGY

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DNA BIOTECHNOLOGY

• Bio 102 Lab

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DNA ELECTOPHORESIS
This technique uses an agarose gel made from
purified seaweed. It is used to separate DNA
molecules according to their length.
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The gel is submersed in a tank filled with a salt
solution that conducts electricity.
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DNA samples are loaded into slots made in the
agarose gel.
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DNA molecules snake through the gel which has
pores in it that tangles up the larger DNA
fragments. The smaller fragments migrate faster
and further.
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A fluorescent dye is added to stain the DNA so it
will glow when placed under ultraviolet light.
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A photograph can then be taken of the gel plate
for analysis and documentation.
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DNA PROFILING
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INVESTIGATE A ROBBERY
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THE CRIME
A woman was hit on the head in her home by a
thief who escaped with her money and jewelry. She
recovered from her injuries but cannot remember
what the thief looks like. You will examine DNA
from blood and hairs from the crime scene and DNA
from blood samples from the victim, her husband,
and a suspect. Then you will try to establish
whether the suspect was at the scene.
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• First, the DNA was extracted from the blood and
  the hair samples and placed in test tubes.

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Here is the equipment for electrophoresis. The
solution in each dropper contains the DNA. The
droppers load the DNA samples into the gel. The
scale measures the length of each DNA strand.
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When the electrical current is applied, the DNA
strands travel down the plate. The larger ones
are towards the top and the smaller ones get all
the way through to the bottom. Which DNA sample
matches the blood sample from the crime scene?
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Does the DNA evidence place the suspect at the
scene of the crime?
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INVESTIGATE A WILL
Percy Davis has just died, leaving his vast
fortune to his children, Percy Junior and Ann. A
man named Alistair claims that he too is one of
Percys children and demands his share of the
money. You will examine DNA from Percy, his wife
Harriet, Percy Junior, Ann, and Alistair to try
to establish whether Alistair has any basis for
his claim.
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DNA samples from each person are loaded into the
wells.
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The DNA fragments are drawn through the gel by
electric current. If the bands for two people
have moved the same distance, there is a match of
DNA at this site.
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Which bands from Harriet match the bands of Percy
Junior?
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The bands highlighted in Harriets profile match
the bands in Percy Juniors profile. Those are
the DNA fragments that he inherited from his
mother.
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Which bands from Percy match the bands of Percy
Junior?
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The bands highlighted in green are the DNA
strands that Percy Junior inherited from his
father. You can see that Percy Junior has
inherited half of his DNA from each of his
parents.
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Now look at the profiles for Alistair and An to
see if they also inherited half of their DNA from
Percy and Half from Harriet.
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Is Percy the father of all three children?
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Is Harriet the mother of all three children?
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Who is not Harriets child?
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Does Alistair have a basis for his claim for part
of Percys fortune?
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References

• http//www.dnalc.org/ddnalc/resources/electrophore
  sis.html
• http//www.biotechnologyonline.gov.au/popups/int_d
  naprofiling.cfm