Heteroduplex Dna is generated by the base pairing between complementary single strands derived from the different parental duplex molecules; heteroduplex DNA molecules occuring during the genetic recombination in vivo and during the hydridization process of different but related DNA strands in vitro. Since the series of the two strands in a heteroduplex is not same, the molecule is not perfectly base-paired; melting temperature of the heteroduplex DNA is dependent upon the number of mismatching of the base pairs.