A recombinant DNA molecule is a hybrid DNA molecule which contains segments of two or more different DNA molecules.  Agarose gel electrophoresis is mainly used to separate the DNA molecule on the agarose gel matrix. The negatively charged molecules of DNA are loaded as a sample on the deeply carved wells on the gel. The loaded sample is induced by a strong electric field which leads to the separation of DNA on the basis of mass and the charge on the DNA. As all the DNA molecules have the same charge so they get aligned on the basis of mass. The smaller DNA molecules move faster and get aligned at the top with the larger segment at the bottom. DNA extraction from agarose gel is divided into many steps. A DNA fragment that is isolated from a cell's nucleus by treating the cells with multienzymes in proper conditions. Once DNA is extracted, to confirm it, it is run on agarose gel. One can see DNA bands in agarose gel by autoradiography. Agarose gel containing extracted DNA shows dark bands when exposed to UV light when the DNA content is high and shows light bands when the DNA content is less. This DNA can be extracted and purified from the gel by the process of elution. DNA is passed through silica columns. The DNA has an affinity for silica gets attached to the membrane and rest of the contents pass through the column.