DNA polymerase:

With the help of DNA polymerases enzymes, nucleotides assemble into DNA molecules. These enzymes are essential to DNA replication and usually work in pairs to create two identical DNA strands from one original DNA molecule.

Molecular scissors:

Restriction enzymes are known as molecular scissors. They cleave DNA at specific recognition sequences called as restriction sites. These enzymes make one incision on each of the two strands of DNA. Example: restriction endonucleases