Plasmid of which bacterium was first time used in recombinant $DNA$ technology?

Restriction enzymes should not have more than one site of action in the cloning site of a vector. Comment.

Which enzyme is used for the separation of genetic material?

The source of $Taq$ polymerase used in $PCR$ is a

Using recombinant technology,genes from a donor cell can be transplanted into a bacterium for $DNA$ replication and protein synthesis. The kinds of cells that can be used as a donor in this technology are

Restriction endonucleases are isolated from some bacteria. Their role in bacteria is