Adenine was first discovered in 1885 by the German physiologist Albrecht Kossel. He isolated adenine from the pancreas of oxen and named it "adenine" derived from the Greek word "aden," meaning gland.

The two remaining positions in the ring are occupied by carbon atoms. (Image: Public Domain) Cytosine was first discovered in 1894 by Albrecht Kossel, a German biochemist. Kossel isolated cytosine ...