An extremely large lactose source is encountered by an E.coli cell in the lumen of the small intestine of a human who just ate an entire carton of ice cream.Which of the following would most likely be a contributor to why the E.coli does not metabolize any of the lactose?
A)Presence of allolactose.
B)Presence of phosphorylated adenylate cyclase.
C)Absence of glucose.
D)Absence of cAMP.

Question

Quizplus · Accepted Answer

The absence of cAMP in E. coli would most likely contribute to the bacterium not metabolizing lactose. cAMP, when present, binds to the cAMP receptor protein (CRP), forming a complex that enhances the transcription of the lac operon, which is necessary for lactose metabolism. Without cAMP, this activation does not occur, even in the presence of lactose.

An Extremely Large Lactose Source Is Encountered by an E