Subsequently, one may also ask, why can't a purine pair with a purine?
You already know that purines bond with pyrimidines, but why can't purines bond with purines or pyrimidines bond with pyrimidines? It's because there is not enough space for two purines to fit within the helix and too much space for two pyrimidines to get close enough together for hydrogen bonds to form between them.
Also Know, what type of bonds can occur between two purine nucleotides? Two hydrogen bonds form between adenine and thymine or adenine and uracil. Complementary pairs always involve one purine and one pyrimidine base *.
Simply so, why does pyrimidine only bond with purine?
Pairing of a specific purine to a pyrimidine is due to the structure and properties of these bases. In DNA base pairing, A pairs with T and C with G. Matching base pairs ( purines and pyrimidines ) form hydrogen bonds. A and T have two sites where they form hydrogen bonds to each other.
Is DNA associated with purines?
Adenine and guanine are found in both DNA and RNA. Hypoxanthine and xanthine are not incorporated into the nucleic acids as they are being synthesized but are important intermediates in the synthesis and degradation of the purine nucleotides.