Q. Into which two groups can the nitrogen-containing bases that form RNA and DNA be classified? What is the criterion used in to that classification?
The nitrogen-containing bases that form RNA and DNA are classified as purine bases and pyrimidine.
By the analysis of the structural formulae of those nitrogen-containing bases it is possible to realize that three of them, , thymine and uracil, cytosine have only one nitrogenized carbon ring. The others, guanine and adenine, have two nitrogenized associated carbon rings.