Haryana PMT Haryana PMT Solved Paper-2010

  • question_answer
    Whose experiments cracked the DNA and discovered unequivocally that a genetic code is a triplet?

    A)  Nirenberg and Mathaei

    B)  Hershey and Chase

    C) Morgan and Sturtevant

    D)  Beadle and Tatum

    Correct Answer: A

    Solution :

    The existence of triplet code was simply an         assumption till 1961, when Nirenberg and            Mathaei proved its existence by experiments.          They were able to synthesise artificial, mRNA     which contained only one nitrogenous base, ie,     uracil. This synthetic poly U sequence was           placed in a cell free system containing protein             synthesising   enzymes   (extracted   from                bacterium E. coli) and 20 amino acids togeth;-     with necessary ATP. During the process, a sma_          polypeptide molecule was produce which was   formed by the linking of phenylalanine. This    suggested that UUU is the code for phenyl          alanine. Nirenberg got Nobel Prize for ha             contributions.


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