The chemical structure of adenine.
The chemical structure of adenosine.
Adenine (A) is a purine base, and forms Watson-Crick base pairs specifically with the uracil pyrimidine. Adenine is joined to ribose at the 9th position to create adenosine.
In Eterna, Adenine is color-coded yellow. When a new puzzle is opened, all nucleotides are assigned to adenine by default.