A plasmid contains the gene for tetracycline resistance and a lacZ gene that has a restriction site in it.Foreign DNA has the same restriction site at its ends.Host bacteria are transformed with the recombinant DNA and grown on medium with tetracycline and X-Gal.Colonies that are producing $\beta$-galactosidase and are resistant to tetracycline are carrying
A) nothing.
B) only lacZ.
C) foreign DNA only.
D) the intact plasmid only.
E) the plasmid with foreign DNA.

Question

Quizplus · Accepted Answer

The colonies producing β-galactosidase and resistant to tetracycline have the intact plasmid, as the insertion of foreign DNA into the lacZ gene would disrupt β-galactosidase production.

A Plasmid Contains the Gene for Tetracycline Resistance and a LacZ