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Which one of the following events occurs when allolactose is not present in the E - VCE - SSCE Biology - Question 6 - 2018 - Paper 1
Question 6
Which one of the following events occurs when allolactose is not present in the E. coli cell? A. LacZ, lacY and lacA genes are switched on. B. LacI does not receiv... show full transcript
Worked Solution & Example Answer:Which one of the following events occurs when allolactose is not present in the E - VCE - SSCE Biology - Question 6 - 2018 - Paper 1
Step 1
C. Molecule Q binds to Section X, preventing the transcription of lacZ, lacY and lacA genes.
Answer
When allolactose is not present in the E. coli cell, the lac operon is typically repressed. In this state, the repressor protein LacI binds to the operator region of the lac operon, effectively blocking transcription of the lacZ, lacY, and lacA genes. This prevents the production of enzymes needed for lactose metabolism, confirming that option C is the correct answer.