NEET Zoology Biotechnology Principles and Processes Questions Solved


EcoRI is used to cut a segment of foreign DNA and that of a vector DNA to form a recombinant DNA. Show with the help of schematic diagrams.            (3 marks)

(i) The set of palindromic nucleotide sequence of base pairs the EcoR I will recognise in both the 

     DNA segements. Mark the site at which EcoR I will act and cut both the segments.

(ii) Sticky ends formed on both the segments where the two DNA segments will join later to form

     a recombinant DNA.

Diagram : 


 (i) Palindromic nucleotide sequence of EcoR I is 


 (ii) Each restriction endonuclease functions by 'inspecting' the length of a DNA sequence. Once it

      finds its specific recognition sequence, it will bind to the DNA and cut each of the two strands

      of the double helix at specific points in their sugar-phosphate backbones. Each restriction

      endonuclease recognises a specific palindromic nucleotide sequence in the DNA.

 (iii) Restriction enzymes cut the stand of DNA between the same two bases on the opposite

       strands. There are overhanging stretches called sticky-ends on each strand. They form 

       hydrogen bonds with their complementary cut counterparts. This stickiness of the ends facili-

       tates the action of the enzyme DNA ligase.

Difficulty Level:

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