What term describes a DNA-cutting enzyme used widely in recombinant DNA technology?

• A. Restriction Enzyme
• B. Gel Electrophoresis
• C. Adaptation
• D. Nondisjunction

Answer: (A)

Restriction enzymes are the DNA-cutting tools used in recombinant DNA technology. They recognize specific short DNA sequences and cleave the DNA at those sites, producing sticky or blunt ends. This precise cutting allows scientists to open plasmid vectors and insert a gene of interest, then seal the pieces with DNA ligase to create recombinant DNA. These enzymes come from bacteria as a defense against phages. In contrast, gel electrophoresis separates DNA fragments by size, adaptation refers to evolutionary change, and nondisjunction is an error in chromosome separation during cell division, none of which describe a DNA-cutting enzyme.