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

  • Nirenberg and Mathaei

  • Hershey and Chase

  • Morgan and Sturtevant

  • Morgan and Sturtevant


A.

Nirenberg and Mathaei

The existence of a triplet code was simply an assumption till 1961 when Nirenberg and Methaei proved its existence by experiment. They were able to synthesise artificial mRNA, which contained only one nitrogenous base, ie, uracil. This synthetic poly-U sequence was then placed in a cell-free system containing protein synthesizing enzymes (extracted from bacterium E. coil) and 20 amino acids together with necessary ATP. During the process, a small polypeptide molecule was produced, which was formed by the linking of phenylalanine. This issuggested that UUU is code for phenylalanine. Nirenberg got Nobel Prize for his contributions.

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select the incorrect statement from the following 

  • Linkage is an exception to the principle of independent assortment in heredity

  • galactosemia is an inborn error of metabolism

  • small population size results in a random genetic drift in a population

  • small population size results in a random genetic drift in a population


Which one of the following is the correct matching of three items and their grouping category?

  • Items

    Group

    Malleus, incus, cochlea

    Ear ossicles

  • Items

    Group

    IIium, ischium, pubis

    Coxal bones of pelvic girdle

  • Items

    Group

    Actin, myosin,

    Rhodopsin

    Muscle proteins

  • Items

    Group

    Actin, myosin,

    Rhodopsin

    Muscle proteins


Removal of introns and joining the exons in a defined order in transcription unit is called

  • splicing

  • tailing

  • transformation

  • transformation


Study the pedigree chart given below.

what does it show?

  • Inheritance of a sex-linked inborn error of metabolism like phenylketonuria

  • Inheritance of a condition like phenylketonuria as an autosomal recessive trait

  • The pedigree chart is wrong as this is not possible

  • The pedigree chart is wrong as this is not possible


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