Question

If a recombinant DNA bearing gene for ampicillin resistance is transferred into E. coli cells and the host cells are spread on agar plates containing ampicillin, then

• A. both transformed and untransformed recipient cells will die
• B. both transformed and untransformed recipient cells will grow
• C. transformed recipient cells will grow and untransformed recipient cells will die
• D. transformed recipient cells will grow and untransformed recipient cells will grow

Answer 1

The correct option is C transformed recipient cells will grow and untransformed recipient cells will die

Transformation is a procedure through which a piece of DNA is introduced in a host bacterium. Bacterial cells with DNA bearing ampicillin resistance gene (transformed recipient cells) when introduced into the plate containing ampicillin will grow. Whereas, cells with DNA not bearing ampicillin resistance gene (untransformed recipient cells) will die. Normally, the genes encoding resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline or kanamycin, etc., are considered useful selectable markers for E. coli. The normal E. coli cells do not carry resistance against any of these antibiotics.