When a vector that uses the lacZ gene as a second marker is used in a cloning experiment, bacteria that contain the recombinant DNA will give rise to
A) red colonies.
B) white colonies.
C) blue colonies.
D) cream colonies.
E) All of the answer choices are correct.

Question

Quizplus · Accepted Answer

Bacteria that contain a recombinant DNA molecule will produce white colonies because the insertion of foreign DNA interrupts the lacZ gene, preventing the bacteria from producing β-galactosidase, which is necessary for metabolizing X-gal (a substrate that produces a blue color when cleaved by β-galactosidase). Therefore, colonies containing recombinant DNA do not produce the blue pigment, resulting in white colonies.

When a Vector That Uses the LacZ Gene as a Second