Heat can disrupt hydrogen bonding between DNA strands WHich

Heat can disrupt hydrogen bonding between DNA strands. WHich of the following DNA strands would denature (come apart) at the highest temerature?

A) 50% AT and 50% GC

B) 10% AT and 90% GC

C) 30% AT and 70% GC

D) 70% AT and 30% GC

Solution

The correct answer would be B) 10% AT and 90% GC ,

Because The percentage of GC content of DNA has a significant effect on its Tm.G-C pairs form three hydrogen bonds, while A-T pairs form only two, the higher the percentage of GC content, the higher its Tm. Thus, A double-stranded DNA rich in G and C needs more energy to be broken than one that is rich in A and T.