Define vector and expression vector.

Define vector and expression vector.

• A. A vector is a DNA molecule used to carry foreign DNA; an expression vector is used only for cloning, not expression.
• B. A vector is an RNA molecule used for gene delivery.
• C. An expression vector is a DNA molecule that carries regulatory elements to drive transcription and translation in a host.
• D. A vector is a lipid used to insert DNA into cells.

Answer: (C)

A vector is a DNA molecule that carries foreign DNA into a host cell, providing a way to propagate the inserted gene inside that cell. An expression vector builds on that idea by including regulatory elements that actively drive transcription and translation of the inserted gene in the host. This means it has a promoter to start transcription, and translation signals and often a terminator to ensure the RNA is properly processed and translated into protein. In practice, a cloning vector might simply shuttle DNA, but an expression vector is designed to make the host express the gene, producing RNA and protein. The other descriptions miss this core point: vectors are DNA, not RNA or lipids, and expression vectors are meant to enable expression, not just cloning.

A vector is a DNA molecule that carries foreign DNA into a host cell, providing a way to propagate the inserted gene inside that cell. An expression vector builds on that idea by including regulatory elements that actively drive transcription and translation of the inserted gene in the host. This means it has a promoter to start transcription, and translation signals and often a terminator to ensure the RNA is properly processed and translated into protein. In practice, a cloning vector might simply shuttle DNA, but an expression vector is designed to make the host express the gene, producing RNA and protein. The other descriptions miss this core point: vectors are DNA, not RNA or lipids, and expression vectors are meant to enable expression, not just cloning.