Question

Which type of restriction enzymes are used in genetic engineering work

• A. Type I
• B. Type II
• C. Type III
• D. Type IV

Hint:

• Type II Restriction Enzymes} are most widely used in genetic engineering because:
  • They recognize specific DNA sequences (restriction sites).
  • They cleave DNA at or very near these specific sites in a predictable manner.
  • They generally require only Mg\(^{2+}\) for activity (simpler cofactor requirements).
• Type I and Type III enzymes have cleavage sites distant from their recognition sites, making them less useful for precise DNA manipulation.

Answer 1

The Correct Option is B

In genetic engineering, the most commonly used restriction enzymes are Type II enzymes. This preference is due to their ability to cut DNA at specific and predictable sequences, known as recognition sites, making them highly effective for precise genetic manipulation.

Explanation of Restriction Enzymes:

• Type I: Cuts DNA at random far from the recognition site. Not useful for precise genetic engineering due to unpredictability.
• Type II: Cuts within or at short specific sequences of the recognition site. Ideal for genetic engineering because they produce consistent fragments.
• Type III: Cuts DNA a short distance away from the recognition site and less predictable than Type II.
• Type IV: Targets methylated DNA, unsuitable for cloning and general genetic engineering.

The specificity and reliability of Type II enzymes make them the preferred choice in applications such as cloning, mapping, and other molecular biology processes.