Tryptophan Synthesis Can Be Controlled by a Process Called Attenuation

Multiple Choice

Tryptophan synthesis can be controlled by a process called attenuation in which the levels of tryptophan in the cell control translation by

A) the binding of the RNA polymerase to the genome.
B) the alteration of the repressor protein.
C) the folding of mRNA into hairpin loops.
D) genes rich in codons for tryptophan.