Question

How many types of restriction endonucleases are present?

• A. Two types
• B. Three types
• C. Four types
• D. Five types

Answer 1

The correct option is C Four types

A restriction enzyme (or restriction endonuclease) is an enzyme that cuts DNA at or near specific recognition nucleotide sequences known as restriction sites. The different restriction endonucleases are classified into four different restriction types I, II, III and IV. Many factors are considered for the classification. Type I enzymes cleave at sites remote from recognition site. Type II enzymes cleave within or at short specific distances from recognition site. Type III enzymes cleave at sites a short distance from recognition site. Type IV enzymes target modified DNA.

Thus, the correct answer is option C.