There are three parts of nucleotide: a nitrogenous base, pentose, and phosphate. There are two types of nitrogenous bases including purines and pyrimidines. Purines are adenine and guanine; pyrimidines - cytosine, thymine, and uracil. The second part of nucleotide is pentose. It is monosaccharide moisture: 2'-deoxyribose in DNA and ribose in RNA. The third part of nucleotide is phosphate group, PO43-.