The DNA (Deoxyribonucleic acid) is made of the monomer units of nucleotides. The nucleotides consist of the phosphate group, nitrogenous base, and a sugar group. The nitrogenous bases of the DNA includes the adenine (A), guanine (G), thymine (T), and cytosine (C). The sequence of the nitrogenous bases on the DNA strands forms the different genes, and this sequence is different in every individual (except the maternal twins).
Hence, the answer is 'phosphate group, sugar group, and nitrogenous base'.