They are enzymes that cleave the nucleotides at the end of the DNA molecule
They are enzymes that cleave the bonds of the DNA from within the molecule(middle part) at specific site
The cleavage by exonuclease results in the formation of nucleotides or nucleosides.
The cleavage by endonuclease results in the formation of oligonucleotides(Four nucleotide residues)
Snake venom, BAL31
S1 nuclease, Dnases, Restriction endonucleases