Nucleotides are the building blocks of nucleic acids (RNA and DNA). On the nucleotide sche- matic below, label the phosphate group, the nitrogenous base, and the pentose (5-carbon sugar). Label the carbon atoms in the sugar ring from 1-5. Note that the carbons are labeled as 'C' in the sugar ring only. off N University of California, Davis 2. What functional group on ANY nucleotide can tell you whether it is a component of DNA or RNA? Which carbon # is this functional group bound to? 3. What nucleotides are unique to either DNA or RNA? unique to DNA unique to RNA are these purines or pyrimidines? 4. What functional groups does the 3' and 5' on DNA represent? (When we say the 3' end of DNA, what are we actually referring to?)