Now, why is that a problem? Well, that's a problem because this H atom actually associates with the other complementary base to form a hydrogen bond. And the hydrogen bonds within our DNA hold the two strands of DNA together. Now, before we examine that in more detail, let's answer the following question. So, what can we say about guanine, when the PH inside our nucleus of the cell is equal to the PKA of the guanine molecule? So, let's suppose, we look at the following curve.