Separation and isolation of DNA fragments in Recombinant DNA Technology
• After the cutting of DNA by restriction enzymes, fragments of DNA are formed. These fragments can be separated by a technique called gel electrophoresis.
• Electrophoresis is a technique of separation of charged molecules, under the influence of an electrical field, so that they migrate in the direction of electrode bearing the opposite charge, through a medium/matrix.
• The most commonly used matrix is agarose, which is a polysaccharide extracted from sea weeds.
• DNA fragments separate according to size, through the pores of agarose gel.
• The separated DNA fragments can be seen only after staining DNA with a compound ethidium bromide (EtBr), as bright orange coloured bands, on exposure to UV radiations.
• The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece. This step is called as elution.
Cloning Vectors (Vehicle DNA)
• The vectors are DNA molecules that can carry a foreign DNA segment and replicate inside the host cell.