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