Each nucleotide consists of, (i) a nitrogenous heterocyclic base which may be purine or pyrimidine. (ii) sugar: deoxyribose (iii) phosphate Related Theory Nucleoside = sugar + base (via glycosidic bond) Nucleotide = Nucleoside + phosphate (via phosphodiester bond) 
A Caution → Nucleosides are the structural subunit of nucleic acids such as DNA and RNA Nucleotides are building blocks of nucleic acids DNA and RNA.