What is the function of restriction enzymes in genetic engineering?

• A. Cut DNA at specific sequences; produce fragments with sticky or blunt ends.
• B. Copy DNA into RNA.
• C. Amplify DNA segments.
• D. Repair damaged DNA.

Answer: (A)

Restriction enzymes are DNA-cutting enzymes that recognize short, specific DNA sequences and cleave the molecule at those sites. This creates fragments with either sticky ends (overhangs) or blunt ends, depending on the enzyme. In genetic engineering, this lets us cut out a gene or a DNA fragment and insert it into a vector; the sticky ends can pair up with complementary ends and be joined by ligase to form recombinant DNA. The other described processes—copying DNA into RNA, amplifying DNA, or repairing damaged DNA—are transcription, DNA amplification, and DNA repair, not what restriction enzymes do.