Question
What are molecular scissors. Explain their role.
Or
How does restriction endonuclease work ?
Solution
Restriction endonuclease enzymes are called molecular scissors which cut double stranded DNA at specific sites called as recognition sites.
Restriction endonuclease provide protection to bacteria against bacteriophages. They are used in genetic engineering as they cut DNA at specific sequence and form recombinant molecules.
Mechanism of their work
Restriction endonucleases inspect the length of DNA sequence and find specific recognition sequence i.e. Palindromic nucleotide sequence in DNA. These enzymes cut the double stranded DNA a little away from centre of these sites but between the same two bases and leave overhanging stretches called sticky ends on each strand.
