The restriction enzymes are called 'molecular scissors' and are responsible for cutting DNA Restriction enzymes belong to a class of enzymes called nucleases. These enzymes are present in bacteria to provide a type of defense mechanism called the 'restriction modification system'. belong to a class of enzymes caned nucleases. These enzymes are present in bacteria to provide a type of defense mechanism called the 'restriction modification system'. This system consist of two components, restriction enzyme and modification enzyme. The term 'restriction' refer to the function of these enzyme in restricting the propagation of foreign DNA of bacteriophage in host bacterium, i.e., cutting of DNA at specific position only.

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