Which segment of DNA would have the higher melting temperatu

Which segment of DNA would have the higher melting temperature? 1) ACC TAC CAC TGG TAG AAT TAC GCG CGA GAA TGG ATG GTG ACC ATC TTA ATG CGC GCT CTT 2) GCA TTG AGA TCC ATC CAT TAG GGC ATC TTG CGT AAC TCT AGG TAG GTA ATC CCG TAG AAC 3) CCA TCA GAT TAT CAT TAC AAA GCG GCC TAC GGT AGT CTA ATA GTA ATG TTT CGC CGG ATG Why?

Solution

The 1st DNA segment is more stable since it has more GC base pairs

DNA high GC-content is more stable than DNA with low GC content.

The GC pair is bound by three hydrogen bonds, while AT and AU pairs are bound by two hydrogen bonds. Also, the higher stabilization is due to interactions of base stacking.