Question

Of the following four 15-bp double-stranded DNA sequences, which will be most stable at higher temperatures? (In other words, which will most likely remain in a double-stranded form?)

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

Answer 1

The DNA sequence with the highest GC content will be most stable at higher temperatures. The sequence CCCGCATCGCCATCG has the highest GC content among the given options.

Step-by-step explanation:

Of the given four 15-bp double-stranded DNA sequences, the one with the highest GC content will be the most stable at higher temperatures. This is because the GC base pair has three hydrogen bonds, while the AT base pair has only two hydrogen bonds. Since more hydrogen bonds contribute to a stronger bond, a DNA sequence with a higher GC content is more difficult to denature and remains in a double-stranded form at higher temperatures.

Let's analyze the sequences to determine the GC content:

1. CCCGCATCGCCATCG: This sequence contains 10 GC base pairs and has a GC content of 66.7%.
2. AAATGCATACATCTT: This sequence contains 5 GC base pairs and has a GC content of 33.3%.
3. CTATACGACATAGCC: This sequence contains 6 GC base pairs and has a GC content of 40%.
4. CATCCTAGCGACTAT: This sequence contains 7 GC base pairs and has a GC content of 46.7%.

Therefore, the DNA sequence with the highest GC content and thus the most stable at higher temperatures is CCCGCATCGCCATCG.