In the lac operon, the repressor inhibits transcription when
a. The repressor is bound to the inducer.
b. The repressor is not bound to the inducer.
c. The repressor is bound to glucose.
d. The repressor is not bound to the operator.

Why are the genes involved in lactose metabolism considered to be an operon?

a. They occupy adjacent locations on the E. coli chromosome.

b. They have a similar function.

c. They are all required for normal cell function.

d. They are all controlled by the same promoter.

A regulon is a set of genes controlled by

a. One type of regulator of transcription

b. Two or more different alternative sigma proteins

c. Many different types of promoters

d. Glucose

Evaluate these statements about regulation of the lac operon. Select True or False for each statement.

T/FThe lac operon is transcribed at the highest rate when extracellular glucose and lactose are abundant.

T/FThe repressor protein is bound to DNA of the operator when lactose is present.

T/FA mutation in the operator is likely to prevent transcription of the lac operon under any condition.

T/FA mutation that alters the catabolite activator protein is predicted to alter the regulation of many different operons.

Activators bind to regulatory sequences in ________ and to ________ polymerase.