Purifying DNA Bands from Agarose Gels

Agarose gel electrophoresis can be used to purify DNA bands after separation by size. In gel extraction, the DNA fragment of interest is cut from the gel and cleaned before later use. This is especially useful in cloning, where pure DNA is needed before ligation, the joining step that links DNA pieces together.

Agarose gel electrophoresis is a technique commonly used to separate DNA molecules by their size.

Agarose — a polysaccharide derived from red algae —  is added to a buffer such as Tris-acetate EDTA (TAE) or Tris-borate EDTA (TBE) and dissolved by heating.

Commonly, 1 gram of agarose is dissolved in 100 milliliters of buffer to form...