What is Gel Electrophoresis?
GEL ELECTROPHORESIS
-It is a laboratory procedure
through which DNA fragments are separated. The technique uses an electric
current to separate DNA fragments. Small DNA fragments move swiftly towards to
positive pole than larger fragments.
-An agarose gel is used to separate
DNA molecules (size varies from several hundred nucleotides to over 10,000
nucleotides). Agar is obtained from red algae (Gracilaria and Gelidium).
-The agarose gel is deluged
in a tank filled with salt solution (as shown in the diagram below) that
conducts electricity.
-DNA fragments are loaded
with the help of a pipette into the slots made in the agarose gel.
-Since the phosphate group
attached to the 5 prime end of a nucleotide carries a negative charge – the overall
DNA molecule can be considered negative in nature. In the electric current –vely
charged DNA moves towards the positive pole.
-Once the fragments are run –
they travel a distance inside the gel as per their fragment size. The gel can be
taken out from the tank and Ethidium bromide fluorescent dye is used to stain
DNA. The dye binds to the DNA double helix and glows when seen under UV light.
The DNA fragment size can be
determined using markers (these are readymade DNA fragments prepared in the laboratory
in various biotechnology based companies – markers have specific DNA sizes)
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