In cloning, what is the role of a restriction enzyme site?

In cloning, what is the role of a restriction enzyme site?

• A. To replicate DNA.
• B. To remove sugars from DNA.
• C. To label DNA with fluorescent tags.
• D. To cut DNA at specific sequences to create ends compatible for ligation into a plasmid.

Answer: (D)

Restriction enzyme sites are specific DNA sequences recognized by restriction enzymes to make cuts. In cloning, this precise cutting creates ends on the insert and on the plasmid vector that are compatible, so the insert can be ligated into the plasmid. The ends may be sticky or blunt, depending on the enzyme, affecting how easily the pieces join. Using matching sites ensures the fragment is inserted at the right place and can be oriented correctly for propagation of recombinant DNA in a host.

Restriction enzyme sites are specific DNA sequences recognized by restriction enzymes to make cuts. In cloning, this precise cutting creates ends on the insert and on the plasmid vector that are compatible, so the insert can be ligated into the plasmid. The ends may be sticky or blunt, depending on the enzyme, affecting how easily the pieces join. Using matching sites ensures the fragment is inserted at the right place and can be oriented correctly for propagation of recombinant DNA in a host.