The promoters of positively controlled operons require activator proteins, because
A) the promoters have nucleotide sequences that bind RNA polymerase weakly, which are not close matches to the consensus sequence.
B) they are needed to bind to the allosteric site of RNA polymerase.
C) RNA polymerase easily recognizes the consensus sequence.
D) they are required to inactivate the repressor proteins.

Question

Quizplus · Accepted Answer

Positively controlled operons require activator proteins because the promoters have nucleotide sequences that bind RNA polymerase weakly, which are not close matches to the consensus sequence. The activator proteins bind to specific DNA sequences near the promoter and help RNA polymerase recognize and bind to the promoter more efficiently.

The Promoters of Positively Controlled Operons Require Activator Proteins, Because