Influence of Agarose Concentration and Electric Field Strength on the Separation of DNA-Fragments During Electrophoresis

Gel electrophoretic separation of DNA fragments has been used extensively in forensic DNA typing. DNAs mobility in gels depends upon fragment length and some other features (Fisher and Dingman 1971). But the mechanism of gel electrophoresis is not well understood. The migration of the DNA molecules through the pores of the matrix must play an important role in molecular weight separations, since the electrophoretic mobility of DNA in free solution is independent of molecular weight(Olivera et al. 1964). The most successful theory of electrophoresis is the reptation theory of deGennes (1971) and Doi & Edwards (1978). The reptation theory describes the migration of polymers in the presence of fixed obstacles. The DNA fragment move along its axis through a “tube” in a neutral gel under the influence of an electric field(Lumpkin et al. 1985). The apparent mobility of DNA fragments (0.5–12kb) decreases with decreasing electric field strength and with increasing gel concentration(Nancy 1985). Separation capacity for DNA fragments is the distance between two fragments in gel electrophoresis.