Exhibit 13A This is a map of the pBR322 plasmid, numbers on the map refer to the base where the site is located.

-Refer to Exhibit 13A. If a recombinant plasmid was obtained inserting DNA into the BamHI site, screening for the recombinant plasmid can be done by the following technique.
A) Plate on nutrient agar plates that contain ampicillin.
B) Plate on nutrient agar plates that contain tetracycline.
C) Plate on nutrient agar plates that contain both ampicillin and tetracycline.
D) Plate on nutrient agar plates that contain ampicillin, followed by replica plating on tetracycline.
E) Plate on nutrient agar plates that contain tetracycline, followed by replica plating on ampicillin.

Question

Exhibit 13A This is a map of the pBR322 plasmid, numbers on the map refer to the base where the site is located.
 
-Refer to Exhibit 13A. If a recombinant plasmid was obtained inserting DNA into the BamHI site, screening for the recombinant plasmid can be done by the following technique.
A) Plate on nutrient agar plates that contain ampicillin. 
B) Plate on nutrient agar plates that contain tetracycline. 
C) Plate on nutrient agar plates that contain both ampicillin and tetracycline. 
D) Plate on nutrient agar plates that contain ampicillin, followed by replica plating on tetracycline. 
E) Plate on nutrient agar plates that contain tetracycline, followed by replica plating on ampicillin.

Quizplus · Accepted Answer

The pBR322 plasmid contains the ampicillin resistance gene (ampR) and the tetracycline resistance gene (tetR) on opposite sides of the plasmid. The BamHI site is located within the ampR gene. If a recombinant plasmid with inserted DNA is obtained using BamHI, the ampR gene will be disrupted, and only bacterial colonies containing the recombinant plasmid will be unable to grow on nutrient agar plates containing ampicillin. Therefore, after plating on ampicillin plates, replica plating on tetracycline plates will allow for the selection of colonies that contain the recombinant plasmid. The replica plating on tetracycline ensures that the colony is not a false positive due to ampicillin-sensitive suppressor mutations. Thus, the best choice is D: Plate on nutrient agar plates that contain ampicillin, followed by replica plating on tetracycline.

Exhibit 13A This Is a Map of the PBR322 Plasmid