Urea and formamide are agents that denature dsDNA by
A) intercalating between base pairs and disrupting van der Waals interactions.
B) forming ionic bonds with the backbone phosphates.
C) competing effectively with the H-bonding between the base pairs.
D) changing the pH to cause hydrolysis.
E) none are true

Question

Quizplus · Accepted Answer

Urea and formamide disrupt the hydrogen bonding between base pairs by competing with the hydrogen bonds for water molecules. This destabilizes the structure of double-stranded DNA and can eventually cause denaturation. Intercalation between base pairs (A) is a mechanism of action for some other denaturing agents, but not for urea and formamide. Forming ionic bonds with the backbone phosphates (B) would likely result in depolymerization of the DNA, rather than denaturation. Changing the pH to cause hydrolysis (D) is not a mechanism relevant to denaturation by urea and formamide.

Urea and Formamide Are Agents That Denature DsDNA by