Exonuclease

Endonuclease

•Exonucleases cleave at the end of the DNA.

•Endonucleases cleave within the DNA strands.

•Acts on single stranded DNA or on nicks or gaps in double stranded DNA.

•They act on double stranded DNA material.

•They produce the respective nucleotides and the process is known as nibbling action.

•They produce fragments of DNA molecules.

•They are end specific and not site specific.

•They are site specific and not end specific.

•They play a vital role in host defence mechanism.

•They play a vital role in producing recombinant molecules.

•For example: λ exonuclease, exonuclease III

•For example: EcoR1, BamH1.