Restriction Enzyme

Enzyme that cleaves DNA molecules at a precisely defined site 

Restriction enzymes are ubiquitous defence proteins in bacteria that cut DNA strands at specifically defined sequences.

There are many different restriction enzymes that each cut DNA at a unique, defined sequence. 

Restriction enzymes are used in genetic engineering as "scissors" to precisely cut out desired DNA fragments. Restriction enzymes are an important factor needed for transferring DNA from one organism to another.