Question

Restriction enzymes commonly used in Recombint D technology are:

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

Hint:

Type II restriction enzymes cut D AT or close to specific palindromic recognition sites without requiring ATP.
This precise cutting makes them indispensable tools for gene cloning.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks to identify which class of restriction endonucleases is routinely utilized in molecular cloning and recombint D procedures.

Step 2: Key Formula or Approach:
Restriction endonucleases cleave double-stranded D at or near specific recognition sequences. They are classified into Types I, II, III, and IV based on cofactor requirements, subunit composition, and cleavage site specificity.

Step 3: Detailed Explation:

• Type II Restriction Enzymes:
• Cleave D precisely at or immediately adjacent to specific, palindromic target recognition sites (typically 4–8 bp long).

• Do not require ATP or $S$-adenosylmethionine (SAM); require only $\text{Mg}^{2+}$ as a cofactor.

• Produce predictable, reproducible D fragments with sticky ($5'$ or $3'$ overhangs) or blunt ends.

• Examples include EcoRI, HindIII, and BamHI.

• Limitations of Other Types:
• Type I and Type III: Cleave D at random positions far away from their recognition sites (e.g., Type I cuts $>1000\ \text{bp}$ away), requiring ATP hydrolysis, making them unsuitable for targeted molecular cloning.

• Type IV: Recognize modified (methylated/hydroxymethylated) D and cut non-specifically.

Step 4: Fil Answer:
Type II restriction endonucleases are the standard choice for recombint D technology.