The nitrogen base pictured is adenine. Is this nucleotide considered a purine or a pyrimidine? There is a molecule, a base of which is formed by 2 fused rings, each of which contains 2 nitrogen atoms in their structure. One ring is five-membered while the other is a six-membered ring. The nitrogen base pictured is adenine. Is this nucleotide considered a purine or a pyrimidine? a. purine b. pyrimidine