Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose)as a potential food source. Which of the following occurs when the lactose enters the cell?
A) The repressor protein attaches to the regulator.
B) Allolactose binds to the repressor protein.
C) Allolactose binds to the regulator gene.
D) The repressor protein and allolactose bind to RNA polymerase.
E) RNA polymerase attaches to the regulator.

Question

Quizplus · Accepted Answer

Allolactose binds to the repressor protein, causing a conformational change that releases the repressor protein from the operator region of the DNA. This allows RNA polymerase to access the structural genes and initiate transcription to produce the necessary enzymes for lactose metabolism.

Allolactose, an Isomer of Lactose, Is Formed in Small Amounts