1, agarose gel electrophoresis principle: agarose gel with complex, material molecules through to resistance, large molecules of material in the surge of resistance, so in gel electrophoresis, the separation of charged particles depends not only on the nature and number of net charge, but also depends on the size of the molecule, which greatly improves the ability to distinguish. However, since its pore size is too large compared to proteins, its molecular sieving effect is negligible for most proteins, and it is now widely used in the study of nucleic acids. Agarose gel electrophoresis is an electrophoretic method using agarose as a support medium. The main difference between its analytical principle and other support electrophoresis is that it has the dual role of "molecular sieving" and "electrophoresis".

2, nucleic acid is an amphoteric electrolyte, its isoelectric point is pH2-2.5, in the conventional electrophoresis buffer (pH about 8.5), nucleic acid molecules with a negative charge, in the electric field to the positive pole. Nucleic acid molecules have charge effect and molecular sieving effect, but mainly molecular sieving effect when swimming in agarose gel. Linear double-stranded DNA molecules in a certain concentration of agarose gel migration rate and the logarithm of the molecular weight of DNA is inversely proportional to the molecules, the larger the molecule is the greater the resistance, but also the more difficult to move in the pores of the gel, and thus the slower the migration.