試題詳解

【已刪除】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