You just need to design one primer inside the insert and the other in the vector. Extra bases are not needed unless your downstream processes require a further enzyme digest. DeltaG ideally should be greater than

(more positive) than −9.0 kcal/mol1.

Dear Virania Putri

if you need just to perfom a colony PCR to check for the presence of the insert and not perform the cloning with this PCR you do not need to add the restrction sites but just the annealing regions.

Restriction site are required to pair the digested PCR with digested vector, which contain the same restriction sites during the cloning

best regards

Manuele

one, when you want to clone it to a plasmid vector and your insert(DNA) doesn't have the restriction enzyme site, you can introduce the restriction enzyme site in your primer set.

two, when you want to create an overlapping primer to amplify circular DNA viruses like begomovirus to amplify the whole genome

.....