In thermal denaturation of double-stranded DNA

Question

Quizplus · Accepted Answer

The value of Tm, which is the temperature at which half of the DNA strands are denatured, is usually dependent on the G + C content of the DNA. This is because G-C pairs have three hydrogen bonds, whereas A-T pairs have only two, leading to a stronger stability in DNA with higher G-C content.

Answer: B 
 The absorption at 260 nm is decreased when the hydrogen-bonded bases become separated. This is known as the hypochromic effect, as the absorption at this wavelength is reduced due to the loss of the pi stacking interaction between the bases in the denatured state.

Therefore, the correct answers are D and B.

In Thermal Denaturation of Double-Stranded DNA