What treatment is applied to a denatured gel to break DNA hydrogen bonds?

The treatment that effectively breaks hydrogen bonds in denatured DNA within a gel is the use of sodium hydroxide (NaOH). When DNA is denatured, it typically involves the separation of the double strands into single strands by breaking the hydrogen bonds that hold the complementary strands together. Sodium hydroxide is a strong base that can disrupt these hydrogen bonds, facilitating the separation of DNA strands effectively.

The other treatments mentioned do not achieve this specific outcome. For instance, soaking in hydrochloric acid might alter the DNA but does not specifically target and break hydrogen bonds in the same efficient manner as sodium hydroxide. Washing with buffer generally serves to maintain the integrity of the DNA without actively breaking any of the interactions between strands. Exposure to UV light can cause damage to DNA through the formation of pyrimidine dimers, but it does not break hydrogen bonds; rather, it can lead to other forms of DNA damage. Thus, sodium hydroxide is the appropriate choice for breaking the hydrogen bonds in denatured gel DNA.