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Gaokao Biology Practice Question

已知 5-溴尿嘧啶 (BU）可与碱基 $A$ 或 $G$ 配对。大肠杆菌 DNA 上某个碱基位点已由 A-T 转变为 $A-B U$, 要使该位点由 A-BU 转变为 $G-C$, 则该位点所在的 DNA 至少需要复制的次数是

  1. A.1
  2. B.2
  3. C.3
  4. D.4

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