thymine

1905-2002 By Erwin chargaff It states that in all DNA, Pyrimidines and Purines must have 1:1 Adenine : Thymine Cytosine : Guanine i.e., the amount of adenine = amount of thymine similarly, the amount of cytosine = amount of guanine. It indicated that DNA is symmetrical.                (A) Double bond (T)    and   (C) triple bond (G)