DNA is made of a double helix strand each made of a glycophosphate backbone and nitrogenous bases as rungs to a ladder. They behave like bases because they are proton acceptors and hence have a net positive charge. Because they have charges they will have electric fields around them. Two pairs of bases on the opposite strands will, therefore, be bound by hydrogen bonds whose strength is governed by Coloumbs law – determined by the charges and the distance between them .
