Agarose gel electrophoresis
Agarose gel electrophoresis is used to separate DNA or RNA molecules by size. Nucleic acids are negatively charged and are moved through an agarose matrix by an electric field (electrophoresis). Shorter molecules move faster and migrate further.
- Cast a gel
- Place it in gel box in running buffer
- Load samples
- Run the gel
- Image the gel
- TAE - better resolution of fragments >4kb;
- TBE - better resolution of 0.1-3kb fragments; TBE is better suited for high-voltage (>150V) electrophoresis than TAE because of its higher buffering capacity and lower conductivity;
|dye||0.5-1.5% agarose||2.0-3.0% agarose*|
|xylene cyanol||4000-5000 bp||750 bp|
|bromophenol blue||400-500 bp||100 bp|
see for recipes: Agarose gel loading dye
- If you are getting unexpected bands on your gel you may want to look at the common issues in agarose gel electrophoresis page.
- If you have no experience with gel electrophoresis or are explaining it to someone new, here is a cute java demo of what happens.
- Wikipedia entry on agarose gel electrophoresis