In cloning experiments, what is the primary purpose of a vector?

• A. To replicate DNA by itself.
• B. Carries the gene of interest into a host cell.
• C. Transcribes RNA.
• D. Translates RNA into protein.

Answer: (B)

The main idea is that a vector serves as a delivery system to get the gene of interest into a host cell so it can be copied and expressed there. In cloning, the vector carries the gene into the host, and provides features like an origin of replication and selectable markers that help maintain and propagate the inserted DNA inside the cell. Once inside, the host’s transcription and translation machinery handle producing RNA from the gene and then making the corresponding protein. The vector itself doesn’t perform transcription or translation, and its primary purpose isn’t to replicate DNA by itself.