High Quality Content by WIKIPEDIA articles! Pyrimidine is 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 is isomeric with two other forms of diazine In DNA and RNA, these bases form hydrogen bonds with their complementary purines Thus the purines ожиыс adenine (A) and guanine (G) pair up with the pyrimidines thymine (T) and cytosine (C), respectively In RNA, the complement of A is U instead of T and the pairs that form are adenine:uracil and guanine:cytosine.  Набор Огневушка2010 г Мягкая обложка, 120 стр ISBN 6130351194.