All of the following are true about the structure of bases found in nucleotides, EXCEPT: (A) Purine ring is nine-membered, (B) Pyrimidine ring is six-membered, (C) Purine and pyrimidine rings are heterocyclic in nature, (D) Imino and lactim form of purine bases are more stable
Answer is D. Purine and Pyrimidine Purines and pyrimidines are nitrogen-containing heterocycles Purines and pyrimidines exhibit tautomerism. The oxo and amino groups of purines and pyrimidines exhibit keto-enol and amine-imine tautomerism. Physiologic conditions strongly our the amino and oxo forms. Purine - 9 membered ring Pyrimidine - 6 membered ring