If bacteria transformed with a recombinant pUC18 plasmid produce white colonies when grown on plates containing ampicillin and X
gal, which of the following is least likely? a. They produce β-lactamase that provides resistance to ampicillin.
b. They carry a vector that contains a DNA fragment inserted into the multiple cloning site.
c. They produce functional β-galactosidase that cleaves X-gal.
d. They carry a vector with a lacZ gene that has been disrupted and rendered nonfunctional.
e. They carry a vector with the bla gene used as the selectable marker.
c. They produce functional β-galactosidase that cleaves X-gal.
Explanation:
β-galactosidase is an enzyme capable of catalyzing the enzymatic hydrolysis of β-galactosides into monosaccharides by hydrolyzing the β-glycosidic bond. On the other hand, X-gal is an analog of lactose composed of galactose, which is widely used in laboratories for the detection of β-galactosidase. In the presence of β-galactosidase, X-gal is hydrolyzed by cleaving its β-glycosidic bond, thereby confirming the presence of β-galactosidase.
Since warm air gradually replaces cold air along a warm front, layers of stratus clouds are formed. A continuous drizzly rain tends to fall since stratus clouds typically cover large areas of the sky. Once the front has passed, however, clear and warm weather tends to follow. the answer is stratus clouds and drizzly rain
There are two types of ossification, direct (intramembranous) or indirect (endochondral). The first originates the skull and face bones; the second occurs in most bones.
