Can a purine pair with a purine?

A always pairs with T and C always pairs with G. A and G are purines, meaning that they have two rings, while T and C are pyrimidines, meaning they have one ring.  Due to the Watson and Crick model, the width of DNA is constant, meaning that there must be a consistant width in each base pairing.  As a result, only a purine can pair with a pyrimidine, giving each base pairing a total of 3 rings.

Explanation:

answer: i don't know

explanation:

you need to provide a picture, otherwise i can't tell you.

if you can provide one, i'd be more than happy to you with this!