So we have hydrogen bonds and London dispersion forces. So a hydrogen bond is a specific type of a dipole dipole interaction, dipole dipole bond. In fact, hydrogen bonds are the strongest type of intermolecular bonds, as we'll see in just a moment. So when we examine our DNA structure, we see that along our bases, on opposite strands of DNA, we have these bases that interact with one another via hydrogen bonds. So one of these bases is guanine. Two other bases are adenine and thymine.