Weak Bonds
These bases contain Nitrogen and these create a twofold strand of DNA through not so strong hydrogen bonds. The nitrogen bases, notwithstanding, have particular shapes and hydrogen bond properties so guanine and cytosine just bond with each other, while adenine and thymine additionally bond only. This matching off of the nitrogen bases is called complementarity. All together for hydrogen clinging to happen by any means, a hydrogen bond benefactor must have a corresponding hydrogen bond acceptor in the base opposite it.