Question

Which of the following enzymes increases the permeability of the bacterial cell to lactose?

• A. Transacetylase
• B. Amylase
• C. $\beta$-galactosidase
• D. Permease

Hint:

Permease is crucial for lactose transport in the lac operon system.

Answer 1

The Correct Option is D

• Lac Operon Function: In the lac operon of E. coli, lactose metabolism involves several enzymes.
  • Permease (lacY gene product): Increases cell membrane permeability to lactose, allowing its entry into the cell.
  • $\beta$-galactosidase (lacZ gene product): Breaks down lactose into glucose and galactose.
  • Transacetylase (lacA gene product): Transfers acetyl groups to lactose derivatives, a minor role.
  • Amylase: Degrades starch, not involved in lactose metabolism.
• Option Analysis:
  • (1) Transacetylase: Incorrect, involved in acetylation, not permeability.
  • (2) Amylase: Incorrect, acts on starch, not lactose.
  • (3) $\beta$-galactosidase: Incorrect, hydrolyzes lactose, not involved in permeability.
  • (4) Permease: Correct, facilitates lactose uptake into the cell.
• Conclusion: The correct answer is (4) Permease.