Explain the roles of the following with the help of an example each in recombinant DNA technology.
(a) Restriction enzymes
(b) Plasmids

(a) Restriction enzymes or restriction endonucleases are essential tools for recombinant DNA technology that cut a DNA molecule at a specific site of four to six nucleotides. Example: EcoRI, HindIII.
(b) Plasmid is extrachromosomal self-replicating circular and double-stranded bacterial DNA. Plasmids act as a cloning vector in recombinant DNA technology. Example - pBR322.