試題詳解

80. Which of the following statements for thermal denatuation of DNA are false?1. The absorption of ultraviolet at 260 nm increases.2.The DNA helical structure unwinds. 3. The covalent N-glycosidic bond between the base and the deoxyribose breaks. 4.The melting temperature of DNA with 60% A+T content is lower than that with 20% G+C content. 5.The double-helical DNA becomes single-stranded DNA at melting temperature.
(A)135
(B)134
(C)145
(D)234
(E)345