Restriction
enzymes are the enzymes that are present in
naturally occurring microorganisms, and cut
the DNA at specific sites e.g, EcoRI at GAATTC,
BamHI at GGATCC, HaeIII at GGCC etc.
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The
DNA molecules that have homologous ends, e.g.
generated by the digestion with the same enzyme,
rejoin in the presence of the enzyme DNA ligase.
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Thus ‘Restriction
enzymes’ and ‘DNA ligase’ are used for the ‘cut’ and ‘paste’ of
DNA
