1. Gel Electrophoresis
By John Tallant

2. Overview
• Gel Electrophoresis is a process that can be
used to separate DNA Fragments
• It uses an electric current to separate the
pieces of DNA that are run through the gel
• The gel used has agarose, a highly purified
seaweed, in it.
• It can separate DNA molecules from hundreds
of nucleotides to hundreds of thousands of
them.

3. Submerging the Gel
• First, a salty solution is poured over the gel in
order to conduct electricity.

4. Loading the Samples
• The DNA samples, colored with blue loading
dye, are placed in the slots made in the
agarose gel.

5. Running the Gel
• Since DNA has a negative charge, it will move
toward the positive end of the gel tank when
electricity is run through the solution.
• The way in which it moves is called
reptation, because it moves like a snake
through the porous gel.
• Smaller fragments move faster and further
than larger fragments, allowing for separation.

6. Recording the Results
• After the gel has been run, the ethidium
bromide that was added to it causes the gel to
glow under ultraviolet light.
• While it is glowing, a picture can be taken of it
to record the results

7. How It Changed Science
• Gel Electrophoresis affected science in a big
way.
• Scientists now had a relatively easy and
definitive way to test and compare DNA
samples.
• It lead the way for more specialized and
complex DNA testing.

8. Forensics
• Gel Electrophoresis has become an absolute
necessity in the field of Forensics.
• It allows them to obtain an irrefutable link to a
possible suspect, or anyone in general.
• The DNA fingerprint it produces is also very
useful in paternity testing.

9. Advantages
• Gel electrophoresis has some advantages:
• Provides a clear link between similar results
• Relatively simple to perform
• Can test DNA from any type of evidence
(hair, blood, skin, etc.)
• Relatively inexpensive

10. Disadvantages
• The disadvantages of gel electrophoresis are:
• The gel can be altered and provide inaccurate
results.
• User error can be catastrophic, depending on
the mistake

11. Ethical Concerns
• There are very few ethical concerns with gel
electrophoresis, as it is only a process by
which you can obtain DNA evidence, and is
usually only used for the good of society, such
as crime fighting, suspect
identification, paternity testing, etc.