Recall that two hydrogen bonds bind A and T,but three hydrogen bonds bind G and C.The stability of DNA is affected by the number of hydrogen bonds,with more bonds promoting more stability.Double-stranded DNA molecules that have greater stability require more heat to be broken into single strands.Which double-stranded DNA molecules would likely require the lowest temperature in PCR?
A) A molecule with 16 percent A
B) A molecule with 23 percent G
C) A molecule with 30 percent C
D) A molecule with 35 percent T
E) More information is required to answer this question.

Question

Quizplus · Accepted Answer

A molecule with 35 percent T would likely require the lowest temperature in PCR because the A/T base pairs only have two hydrogen bonds, making them easier to break apart compared to the G/C base pairs, which have three hydrogen bonds. Therefore, a DNA molecule with fewer G/C base pairs and more A/T base pairs (higher percentage of T) would require less heat to be broken into single strands, making it easier to denature and amplify in PCR.

Recall That Two Hydrogen Bonds Bind a and T,but Three