Question

Which type of restriction enzyme is most widely used?

• A. Type I
• B. Type II
• C. Type III
• D. Types I and II

Answer 1

The correct option is B Type II

• There are three classes of restriction enzymes, labeled types I, II, and III. Type I restriction systems consist of a single enzyme that performs both modification (methylation) and restriction activities.
• These enzymes recognize specific DNA sequences, but cleave the DNA strand randomly, at least 1,000 base pairs (bp) away from the recognition site.
• Enzymes of this kind are the principal ones available commercially.
  Hence, option B is correct.