Question

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 palindromic nucleotide sequence of base pairs the Eco RI-will
recognise in both the DNA segments. mark the site at which Eco RI will act and-cut both the segments., (ii) Sticky ends formed on both the segments where the two DNA segments will join later to forma recombinant DNA.

Answer 1

1. 
   

2. Palindromic nucleotide sequence of EcoR I is

5' GAATTC 3'

3' CTTAAG 5'

3. 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. 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 facilitates the action of the enzyme DNA ligase.