1. The two types of nucleases are exonucleases and endonucleases.
2. Exonucleases remove nucleotides from the ends of the DNA.
3. Endonucleases are those enzymes that have ability to make cuts at specific positions within the DNA molecule.
4. Of the endonucleases, restriction endonucleases serve as the molecular scissors in genetic engineering experiments.
5. They are used for cutting DNA molecules at specific predetermined sites. This is needed for gene cloning or recombinant DNA technology.