Phosphodiester bond is covalent bond that links a phosphate group and a sugar group, by means of an oxygen bridge, in the sugar-phosphate backbone of a nucleic acid molecule. In the bond, the phosphate group is connected to carbon 5' of the sugar residue of its own nucleotide and carbon 3' of the sugar residue of the next nucleotide. The bonding gives DNA helix its antiparallel nature.