Question

What are restriction enzymes and how are they used to cut DNA?

Answer 1

Answer and Explanation:

A restriction enzyme is a type of endonuclease enzyme  that recognizes  a specific short nucleotide sequences on the DNA and  cuts the DNA only at palindromic sites. There are different types of restriction enzymes:

1. Type I restriction enzyme – It cuts at sites far  from the recognition site and requires both ATP and S-adenosyl-  L-methionine as cofactor to function.  

2. Type II restriction enzymes – It cleaves at short-specific distances from the recognition  site and mostly  requires magnesium to function.

3. Type III restriction enzymes – It recognizes two  separate non-palindromic sites and cleaves at 20–30 base  pairs away from a recognition site. It requires both ATP  and S-adenosyl-L-methionine  .

The restriction enzymes cleave DNA sequences producing either sticky or blunt ends that can be ligated with other sequences.