Nucleic acids (DNA and RNA) are the polymers of nucleotides. Each nucleotide is made up of 3 components: 1) a pentose sugar, 2) a phosphate, and 3) a nitrogenous (nitrogen-containing) base. A nucleotide without the phosphate group is called a nucleoside. The nitrogenous bases are derivatives of two compounds: pyrimidine and purine. The bases and pentose sugar are heterocyclic compounds. The carbons of the pentose sugar are given a prime (‘) designation to differentiate them from the numbered atoms of the nitrogenous bases.