Cells that are His⁻, Strᴿ could be isolated from a mixed sample by using a medium containing
A) streptomycin
B) histidine AND glucose
C) penicillin AND streptomycin
D) glucose AND streptomycin
E) histidine AND streptomycin

Question

Cells that are His⁻, Strᴿ could be isolated from a mixed sample by using a medium containing
A) streptomycin
B) histidine AND glucose
C) penicillin AND streptomycin
D) glucose AND streptomycin
E) histidine AND streptomycin

Quizplus · Accepted Answer

The cells that are His⁻, Strᴿ are sensitive to histidine and resistant to streptomycin. Therefore, a medium containing histidine and streptomycin would allow for the growth of only the His⁻, Strᴿ cells. Choice A and D include only streptomycin, which would not select for the His⁻ cells. Choice B includes both histidine and glucose, but glucose is not necessary for selecting the His⁻, Strᴿ cells. Choice C includes penicillin, which is not relevant to the selection of these specific cells.

Cells That Are His⁻, Strᴿ Could Be Isolated from a Mixed