Analysis of DNA by Agarose Gel Electrophoresis

Electrophoresis through agarose or polyacrylamide gels is used to separate, analyze, identify, and purify DNA fragments. The technique is simple, rapid to perform, and capable of resolving fragments of DNA that cannot be separated adequately by other procedures, such as density gradient centrifugation. The location of bands of DNA within the gel can be determined directly by staining with low concentrations of fluorescent intercalating dyes, such as ethidium bromide or SYBR Gold; bands containing as little as 20 pg of double-stranded DNA can then be detected by direct examination of the gel in ultraviolet (UV) light. If necessary, these bands of DNA can be recovered from the gel.