試題詳解

11. Double-stranded DNA absorbs less UV light than single-stranded DNA because:
(A) base stacking in double-stranded DNA increases the absorbance of white light and causes a decrease in the amount of UV light it can absorb. This decrease in UV absorbance is called the hyperchromic effect.
(B) the bases are on the inside of the helix, inaccessible to the UV light in double-stranded DNA.
(C) in single-stranded DNA the bases are not interacting, which adds to the light already absorbed by the pentose rings.
(D) of the hypochromic effect that results when hydrogen bonding and base stacking in double- stranded DNA limits resonance in the aromatic rings of the bases.