Need help!! About base pairing.

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    • #6186
      CyLMH
      Participant

      I met this problem in the tutorial,

      why U cannot replace T in the DNA double helix?

      I guess it might be because the distance may be different (not 1.08nm, as is the distance of A-T & C-G pairs).

      Anyone can give specific explanation?

      Thx a lot!!

    • #57752
      MrMistery
      Participant

      i’ve always thought that the DNA polymerase can only work with T, not U… I never actually read this anywhere, so i may be wrong..

    • #57757
      sachin
      Participant

      Me too never read about U replacing T in DNA.

      It may deform DNA helix. ❓

    • #57759
      druid
      Participant

      Any uracil found in DNA is removed by mismatch repair system.

      "One of the most common reactions in which a base is directly removed from DNA is catalyzed by uracyl-DNA glycosylase. Uracil occurs in DNA most typically bacuase of ( spontaneous ) deamination of cytosine. It is recognised by glycosylase and removed"

      Genes VIII, Lewin, p451

    • #57825
      CyLMH
      Participant
      quote druid:

      Any uracil found in DNA is removed by mismatch repair system.

      “One of the most common reactions in which a base is directly removed from DNA is catalyzed by uracyl-DNA glycosylase. Uracil occurs in DNA most typically bacuase of ( spontaneous ) deamination of cytosine. It is recognised by glycosylase and removed”

      Genes VIII, Lewin, p451

      Ok, thx. I guess this is the answer. I asked one of my schoolmate, and he gave me a similar answer.

      Because U has a similar structure to C, so it will be corrected to C if it is in the DNA structure. For the reason above, it cannot be present in DNA.

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