Cells will not express genes that are on dna fragments floating in their cytoplasm. to express the genes on such a fragment, you will need a vector, a dna construct that will deliver your genes into the new cell and will have the necessary dna promoter sequences to initiate transcription. the vector that will suit your needs for this project is an expression plasmid. a plasmid is a small circular strand of a dna double helix that will have a site for insertion of your dna fragment and the necessary promoters for expression of the genes. the sequence of the circular plasmid will be digested with the same restriction enzyme you used to cut out the fragment from the bacterial chromosome. the fragment will then be fused into the opened plasmid using the enzyme dna ligase. the ends of the fragment will be paired with the cut ends of the plasmid based on dna nucleotide sequences. since the same enzyme was used to cut the fragment and the plasmid, this will result in the ends having identical dna base sequences, which repair enzymes will recognize and ligate the dna sequences together. the question now is which plasmid of the hundreds of commercially available plasmids you should use. which plasmid characteristics would be required for optimal expression of a dna fragment to yield a peptide