Eco RI 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.
(i) The set of palindronic nucleotide sequence of baes pairs the Eco RI will recognise in both the DNA segment. Mark the site at which Eco RI will act and cut both the segments.
(ii) Sticky ends of formed on both the segments where the two DNA segments will join later to form a recombinant DNA.

Explanation

For figure See Q. 29 (b), Set-I., Delhi Board-2008.
(i) 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 strand of the double helix at specific points in their sugar phosphate backbones. Each restriction endonuclease recognises a specific palindromic nucleotide sequence in the DNA. (ii) Restriction enzymes cut the strand of DNA between the same two bases on the opposite strands. These are over hanging stretches called sticky ends on each strand. They form hydrogen bonds with their complementary cut counter parts. The stickness of the ends facilitates the action of the enzyme DNA ligase