when a bacterial plasmid transfer a piece of foreign DNA to a Host Cell, What does the plasmid serve as?

Question

is it vector

Answer 1

The plasmid itself is the piece of DNA that is transferred to the host cell. It is a small circular peice of DNA separate to the bacteria's primary DNA stand, and often holds the sequences for one or more extra genes that are not required for life, but perhaps make it a little easier.

Answer 2

Not only does the plasmid carry in the piece of DNA, but, more importantly, the plasmid generally also contains various elements, including promotors and regulators, that allow the foreign DNA to be expressed. Otherwise the DNA (without promotors, etc.) would be essentially inert.

Answer 3

The term that's used to describe the function of a plasmid is "vector".