In gene cloning, what is the purpose of a plasmid or viral vector?

• A. To carry the gene into target cells.
• B. To degrade the gene.
• C. To cut DNA.
• D. To replicate the gene in bacteria.

Answer: (A)

Vectors like plasmids or viral vectors act as delivery vehicles that carry the gene of interest into target cells. They provide a stable framework to bring the DNA into the host, where it can be replicated and, if designed for expression, transcribed and translated. This delivery role is essential for cloning because introducing foreign DNA into cells efficiently is how you propagate and study the gene. The other options don’t fit: degrading the gene would destroy it; cutting DNA is done by enzymes like restriction nucleases, not by the vector itself; and while the vector does replicate within the host to maintain the gene, its primary purpose is to deliver and maintain the gene in the cells for propagation and expression.