Gel electrophoresis is used for

Gel electrophoresis is a technique in molecular biology that is used to separate DNA fragments (or RNA and proteins) based on their size and charge. DNA molecule has negative charges on the sugar-phosphate backbone due to the presence of Phosphate molecule (PO4) 3- molecule. As the DNA molecules have the same amount of charge per mass, DNA fragments are separated according to their size in during electrophoresis.