And that's exactly why at around this range we see a tremendous decrease in the number of DNA molecules that exist in a double helix form. Because around this PH, half of these guanine have lost their age and have been deprotonated. Now, they cannot form those stabilizing hydrogen bonds. So when the PH of the cell equals the PKA of guanine, so when the PH is 9.7, the concentration of the protonated guanine will equal to the concentration of deprotonated guanine. That is exactly half of the guanine bases will be deprotonated. Now, that's a problem because guanine participates in hydrogen bonds which are responsible for holding the two strands of DNA together.