AP Biology question on DNA technology?

To express a protein (for instance Bovine Serum Albumin) you take your gene of interest i.e. BSA and take a bacterial plasmid it could by any one as lot of them are available in the market (you can term it as your expression vector). You do the PCR of your insert i.e BSA gene in such a way that you increase the number of copies + adding restriction sites which will fit to your vector. You do restriction digestion of you vector then ligate both insert and vector together. Transform in a suitable bacterial host and express your protein. To understand how this is done in detail you can read any scientific article involving expression of any protein.