The three components of a nucleotide are a nitrogenous base, a pentose sugar, and a phosphate group. The nitrogenous base can be either a purine or a pyrimidine and is attached to the 1 carbon of the pentose sugar. The pentose sugar is a five-carbon sugar, either ribose in RNA or deoxyribose in DNA, and is attached to the nitrogenous base at the 1 carbon and to the phosphate group at the 5 carbon. The phosphate group is attached to the sugar by a phosphodiester bond, forming the backbone of the DNA or RNA molecule.