(a) Mention the difference in the mode of action of exonuclease and endonuclease.
(b) How does restriction endonuclease function?
Answer (a) Differences between action of exonucleases and endonucleases are as follows :
Restriction nucleases act as molecular scissors or chemical scalpels. 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.
