If a nitrogenous base is composed of two of these rings, it is known as a purine, but if it is only composed of one ring, it is called a pyrimidine. Purines and pyrimidines naturally bind to one ...

The purine structure consists of a pyrimidine ring (positions 1 to 6) fused to an imidazole ring (positions 7 to 9). Adenine and guanine, the two most common purines in DNA and RNA, share this core ...

This diagram depicts the chemical structure of pyrimidine, a six-membered aromatic ring with two nitrogen atoms at positions 1 and 3 (highlighted in blue). The remaining positions are occupied by ...