Prof. Dr. Sevgi ERTUĞRUL KARATAY
DNA gel electrophoresis
Gel electrophoresis is a widely used technique for the analysis of nucleic acids and proteins. Agarose gel electrophoresis is
routinely used for DNA preparation and analysis.
Gel electrophoresis is a procedure that separates DNA molecules according to their velocity of movement along a gel under the
influence of an electric field.
Agarose gel electrophoresis is used to determine the presence and size of PCR products. Conducting PCR products in DNA gel
electrophoresis indicates the presence of E. coli plasmids.
How does DNA gel electrophoresis work?
DNA is a negatively charged molecule (due to phosphate groups).
When placed in an electric field, DNA migrates from the negative pole to the positive pole.
The polymerized agarose (sulfate-free agar) is a porous structure that allows the movement of DNA.
How does DNA gel electrophoresis work?
Because of the porous nature of the agarose, DNA fragments of different sizes are separated from each other in proportion to
their size as they move from the negative pole to the positive pole.
Large DNA molecules walk more slowly, while small DNA molecules move faster.
The size and location of the DNA fragment of interest can be determined by means of a known marker (DNA marker).
DNA gel electrophoresis
1) Prepare 500 ml of TAE buffer (10X).
2) 1% agarose gel is prepared. (Agarose is dissolved in 100 mL of TAE by heating, then 1 uL of ethidium bromide is added.
3) The prepared agarose combs are poured into the placed gel tank.
4) Loading dye is added to E. coli plasmid DNA. This process is carried out on parafilm dye and DNA is mixed.
DNA gel electrophoresis
5) TAE buffer is added to the tank.
6) The combs of the gel are slowly removed and loaded with 3 uL of marker DNA into the 1st well and the DNAs to 4 uL into the
other wells.
7) Adjust the power supply to 5 V/cm.
8) The samples are examined under UV light.
