Question
  1. Write the palindromic nucleotide sequence for the following DNA segment:

5' - GAATTC - 3'

  1. Name the restriction endonuclease that recognises this sequence.
  2. How are 'sticky ends' produced? Mention their role.

Answer

  1. 5' - GAATTC - 3'
3' - CTTAAG - 5'
  1. EcoRI is the restriction endonuclease that recognizes this palindrome.
  2. When the restriction enzyme cuts the DNA strands a little away from the centre of the palindromic sequence, between the same two bases on both the strands, sticky ends are produced.
  • The stickiness of the ends facilitates the action of the enzyme DNA-ligase.

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