Question
(a) Mention the difference in the mode of action of exonuclease and endonuclease.
(b)How does restriction endonuclease function?Solution
The difference between the mode of action of endonuclease and exonuclease is that Exonuclease removes nucleotides from the ends of the DNA whereas Endonuclease makes cut at specific positions within the DNA.
(b) Restriction endonuclease functions by inspecting the entire length of the DNA sequence. When it finds the specific recognition sites it binds to the DNA molecule and cuts both the strands at specific palindromic sites in their sugar-phosphate backbone.
e.g. Eco R1 cuts the DNA at following pallindromic sequences.
|
5' G A A T T C 3'
3' C T T A A G 5'
|
