What happens when lactose is present in the environment of E. coli?
Practice Questions
Q1
What happens when lactose is present in the environment of E. coli?
The lac repressor binds to the operator
Transcription of the lac operon is inhibited
The lac repressor is inactivated
cAMP levels decrease
Questions & Step-by-Step Solutions
What happens when lactose is present in the environment of E. coli?
Step 1: Lactose enters the environment where E. coli bacteria are present.
Step 2: Lactose molecules bind to a protein called the lac repressor inside the E. coli.
Step 3: When lactose binds to the lac repressor, it changes the shape of the repressor (this is called a conformational change).
Step 4: The change in shape makes the lac repressor unable to bind to the DNA, which means it cannot block the genes it usually controls.
Step 5: With the repressor inactive, the genes of the lac operon can be turned on (transcribed), allowing the bacteria to use lactose as a food source.
