In thermal denaturation of double-stranded DNA
A) the value of Tm is usually dependent on the G + C content of the DNA.
B) the absorption at 260 nm is decreased when the hydrogen-bonded bases become separated.
C) G-C pairs are the main contributors towards the hyperchromic effect observed upon thermal denaturation.
D) the bases undergo a shift to the enol form.
E) the relative viscosity remains unchanged.

Question

Quizplus · Accepted Answer

The melting temperature (Tm) of DNA is influenced by the G + C content because G-C pairs, which have three hydrogen bonds, are more stable than A-T pairs, which have two hydrogen bonds. This makes DNA with higher G + C content have a higher Tm.

In Thermal Denaturation of Double-Stranded DNA