What is a vector?

• A. Any living organism that can carry a disease-producing virus.
• B. A carrier protein that transports molecules across membranes.
• C. A DNA sequence that codes for a protein.
• D. A type of virus that infects plants.

Answer: (A)

A vector in biotechnology is a vehicle that delivers foreign genetic material into a host cell so scientists can clone, modify, or express a gene. The most common vectors are plasmids used in bacteria or engineered viral vectors. They’re designed to carry the gene of interest and to replicate and express in the host, often with features like an origin of replication and a selectable marker to identify cells that have taken up the vector.

This definition is distinct from epidemiology, where a vector is an organism that transmits a disease-causing agent; from a carrier protein that moves molecules across membranes; from a DNA sequence that codes for a protein (which is a gene, not a delivery tool); and from a plant virus itself (an infectious agent, not the cloning delivery vehicle).