Question

(a) Explain the significance of 'palindromic nucleotide sequence' in the formation of recombinant DNA.

(b) Write the use of restriction endonuclease in the above process. [3]

Answer 1

(a) Palindromic nucleotide sequence is the recognition sequence present both on the vector and on a desired or alien DNA for the action of the same restriction endonuclease to act upon. Each restriction endonuclease recognises a specific palindromic nucleotide sequence in the DNA and then cuts each of the two strands of the double helix at the specified points. [1.5]

(b) The same restriction endonuclease binds to both vector and the foreign DNA and cuts each of the two strands of the double helix at specific points in their sugar phosphate backbone of the recognition sequence. This creates overhanging stretches called sticky ends. These sticky ends are then joined by DNA ligase to form recombinant DNA. [1.5]