Gel electrophoresis is a process that uses an electric current to separate DNA fragments of varying sizes placed in an agarose gel. Smaller DNA fragments move faster and further through the gel than larger fragments, allowing separation. After running the current through the gel, DNA bands can be visualized under UV light and photographed. Gel electrophoresis revolutionized science by providing an easy way to test and compare DNA samples, leading to more advanced DNA testing with applications in forensics, paternity testing, and criminal investigations.

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.