This image illustrates the chemical structure of a purine molecule, highlighting the numbering of the carbon and nitrogen atoms. The purine structure consists of a pyrimidine ring (positions 1 to 6) ...
This image illustrates the chemical structures of the five main nucleobases found in DNA and RNA. The pyrimidines, thymine (DNA), uracil (RNA), and cytosine are shown on top while the purines, adenine ...