Question

Of the following four 15-bp double-stranded DNA sequences, which will be most stable at higher temperatures?

a) CCCGCATCGCCATCG
b) AAATGCATACATCTT
c) CTATACGACATAGCC
d) CATCCTAGCGACTAT

Answer 1

Sequence a) CCCGCATCGCCATCG will be most stable at higher temperatures due to its highest GC content, which forms three hydrogen bonds, providing greater stability than AT pairs with only two hydrogen bonds.

Step-by-step explanation:

The stability of double-stranded DNA at high temperatures is significantly influenced by the base pairing between the nucleotides, specifically between guanine (G) and cytosine (C), and adenine (A) and thymine (T). A GC pair forms three hydrogen bonds, whereas an AT pair forms two hydrogen bonds. As a result, DNA sequences with higher GC content are more stable and more resistant to denaturation at high temperatures compared to those with higher AT content. Of the four sequences provided, sequence a) CCCGCATCGCCATCG would likely be the most stable at higher temperatures because it has the highest GC content.