#Everyone is a Writer

What are the necessary components of a plasmid? 

A plasmid contains three necessary functional regions: an origin of replication, a polylinker to clone the gene of interest (called multiple cloning site where the restriction enzymes cleave), and an antibiotic resistance gene (selectable marker). Besides, promoter region, which drives transcription of the target gene, is a vital component for expression vectors: determines which cell types the gene is expressed in and amount of recombinant protein obtained. Some plasmid also have selectable markers for use in other cell types.