Definition of Expression Vector
The expression vector is a cloning vector that is composed of a promoter that helps the gene of interest to transcribe into RNA. This transcription happens when the vector is inserted into the host cell. A vector is actually a plasmid which is circular in shape and is known as extra-chromosomal DNA that is found in the bacterial cells. This plasmid is cut and a particular gene i.e. gene of interest is introduced into it.
This plasmid is then transferred into the host cell where it will make copies of it. This plasmid has regulatory sequences as well as promoter regions that are required for the processes of transcription and translation. In this way, the gene of interest is expressed and the required protein is formed.