The DNA is composed of four nucleotides (deoxyadenosine, deoxycytidine, deoxythymidine and deoxyguanosine), to the exclusion of other possible deoxynucleotides.
DNAet var sammensat af fire nukleotider (deoxyadenosine, deoxycytidine, deoxythymidine og deoxyguanosine), for at udelukke andre mulige deoxynukleotider.