KVPY Sample Paper KVPY Stream-SX Model Paper-21

  • question_answer
    The restriction fragment shown below contains a gene whose recessive allele is lethal. The normal allele has restriction sites for restriction enzyme pst I at sites I and II. The recessive allele lacks restriction sites I. An individual who had a sister with the lethal trait is being tested to determine if he is a carrier of that lethal trait.
    Which of the band patterns would be produced on a gel if he is a carrier?





    Correct Answer: D

    Solution :

    · Normal allele · · Recessive allele · · If an individual is a carrier he will have 1 copy of the normal allele and 1 copy of the recessive allele. When digested with restriction enzyme pst I, there will be 5 restriction fragments formed · · Gel electrophoresis is used for separating the mixture of fragments obtained through a gel in an electrical field. The negatively charged DNA molecules migrate toward the positive electrode at a rate inversely proportional to their length. Thus, the largest fragment will be closest to the negative electrode, while the 3 smaller fragments which are similar in length are closer to the positive electrode.

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