Assume the two E.coli strains shown below are allowed to conjugate.
Hfr: pro⁺,arg⁺,his⁺,lys⁺,met⁺,ampicillin-sensitive
F-: pro⁻,arg⁻,his⁻,lys⁻,met⁻,ampicillin-resistant
What supplements would you add to glucose minimal salts agar to select for a new recombinant cell that is lys⁺,arg⁺,amp-resistant?
A)ampicillin,lysine,arginine
B)lysine,arginine
C)ampicillin,proline,histidine,methionine
D)proline,histidine,methionine
E)ampicillin,proline,histidine,lysine

Question

Assume the two E.coli strains shown below are allowed to conjugate. 
Hfr: pro⁺,arg⁺,his⁺,lys⁺,met⁺,ampicillin-sensitive
F-: pro⁻,arg⁻,his⁻,lys⁻,met⁻,ampicillin-resistant
What supplements would you add to glucose minimal salts agar to select for a new recombinant cell that is lys⁺,arg⁺,amp-resistant?
A)ampicillin,lysine,arginine
B)lysine,arginine
C)ampicillin,proline,histidine,methionine
D)proline,histidine,methionine
E)ampicillin,proline,histidine,lysine

Quizplus · Accepted Answer

To select for a new recombinant cell that is lys⁺, arg⁺, and ampicillin-resistant, you need to add ampicillin to select for cells that are resistant (inherited from the F- parent), and proline, histidine, and methionine to compensate for the auxotrophies of the F- parent that were not specified to be corrected by recombination. Lysine and arginine do not need to be added because the recombinant is already lys⁺ and arg⁺, so it can synthesize these amino acids on its own.

Assume the Two E