|Section2= |Section3= }} Pyrimidine's a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring. It's isomeric with two other forms of diazine. Nucleotides Three nucleobases found in nucleic acids (cytosine, thymine, and uracil) are pyrimidine derivatives: In DNA and RNA, these bases form hydrogen bonds with their complementary purines. Thus the purines adenine (A) and guanine (G) pair up with the pyrimid… (More on Pyrimidines)