Draw 1 tautomeric form of thymine.

Which of the following nucleotide bases are present in equal amounts in $DNA$ due to base pairing rules?

The four nitrogenous bases commonly found in DNA are:

Select a correct structure for U.

Draw a structure for cytosine.

Draw the other 2 tautomeric forms of cytosine. 

Which letters represent the four nitrogenous bases found in $DNA$?

Which of the following nitrogenous bases is not found in $m\mathrm{RNA}$?

Which two classes of biomolecules commonly include $N$ in their structures?