If you were to try and pair a thymine with a cytosine (a non watson-crick base pairing), then would you expect to see any stability with respect to the hydrogen bonding (assuming the geometrical configurations of both bases were favorable to each other)? if yes, then how many hydrogen bonds could form between these two bases? a) yes, two hydrogen bonds could form between thymine and cytosine. b) yes, one hydrogen bond could form between thymine and cytosine. c) no, hydrogen bonds cannot form between thymine and cytosine. d) yes, three hydrogen bonds could form between thymine and cytosine

The correct answer is A) Yes, two hydrogen bonds could form between thymine and cytosine

Explanation:

Given an ideal scenario where geometric boundaries were crossed, then two pyrimidines (which is the case) could form hydrogen bonds. As their chemical components allow them to form two or three bonds depending on the corresponding complementary base, they would be able to establish two hydrogen bonds, one between O and H-N and the other one between N-H and N. Anyway, this kind of arrangement would have to consider some other characteristics of the DNA structure. One of them is that the helicoidal disposition highly depends on the fact that some bases form two or three bonds. And the other one is the disposition of this arrangement in the space.

answer: the answer is b