Restriction enzymes

Options

A. Are endonucleases which cleave DNA at specific sites
B. Make DNA complementary to an existing DNA or RNA
C. Cut or join DNA fragments
D. Are required in vectorless direct gene transfer.

Answer

A

Explanation

Restriction enzymes are endonucleases which cleave DNA at specific sites. They are originally extracted from the bacterium E.coil. Type I restriction enzymes bind to a recorgnitionn site of duplex DNA and cleave one strand only. Type II restriction enzmyes are more valuable in gene manipulation and cleave the dulpex at specific target sites at or near the binding site.