DNA is fundamental to the biology of all life on Earth, but how many of us actually know what it is or what it's made of?

The purine structure consists of a pyrimidine ring (positions 1 to 6) fused to an imidazole ring (positions 7 to 9). Adenine and guanine, the two most common purines in DNA and RNA, share this core ...

Inosine is a nucleoside containing hypoxanthine and ribose. It differs from adenosine by the absence of an amino group at the 6 position of the purine ring. (Image: Public domain, via Wikimedia ...