Question

Suc- strains cannot utilize sucrose, trp- strains cannot synthesize tryptophan. In the generalized transduction of a suc-trp- strain of E. coli using bacteriophage derived from a suc+trp+ cell, what medium would select for suc+ and trp+?

A) a minimal medium
B) a minimal medium + sucrose
C) a minimal medium + tryptophan
D) a minimal medium + sucrose + tryptophan
E) none of the above

Answer 1

B) a minimal medium + sucrose

Step-by-step explanation:

Suc+ ⇒ can utilize sucrose, so you have to add sucrose to the medium.

Trp+ ⇒ can synthesize tryptophan, so it is not required to add tryptophan to the medium because the cell can produce it.

According to this, to select for suc+ trp+ you have to only add sucrose to the medium. Thus, it will only grow the cells that can utilize sucrose and can synthesize tryptophan.

Therefore, the correct option is: B) a minimal medium + sucrose