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

Question

Quizplus · Accepted Answer

The LacZ gene encodes for β-galactosidase enzyme that hydrolyzes lactose into glucose + galactose. The enzyme cleaves a chromogenic substrate 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-gal) if present in the medium, producing a blue color. However, if there is a disruption in the LacZ coding sequence due to insertion of foreign DNA, the beta-galactosidase enzyme is not produced, and X-gal is not hydrolyzed, creating a white colony. Therefore, the correct answer is B, white colonies.

When a Vector That Employs the LacZ Gene as a Second