In an experiment in recombinant DNA, the colonies that contain the correct recombinant DNA have turned blue.The most likely selective marker being used is
A) GFP.
B) an antibiotic resistance gene.
C) lacZ.
D) a plasmid.
E) a phage.

Question

Quizplus · Accepted Answer

The lacZ gene encodes for beta-galactosidase, an enzyme that breaks down the artificial substrate X-gal to produce a blue color. Therefore, if a recombinant plasmid containing the lacZ gene is successfully inserted into a host bacteria, the colonies that contain the correct recombinant DNA will turn blue when grown on media supplemented with X-gal. This allows for easy selection of bacteria that have taken up the recombinant DNA. GFP is a fluorescent protein and is not used as a selective marker in this scenario. Antibiotic resistance genes are commonly used as selective markers, but they do not produce a color change like the lacZ gene. Plasmids and phages are not selective markers, but rather types of vectors used to introduce recombinant DNA into host cells.

In an Experiment in Recombinant DNA, the Colonies That Contain