Which of the following statements is FALSE?

• A. An inducible operon is turned on by the presence of an inducer molecule.
• B. An inactive repressor protein requires binding of a corepressor molecule to become active.
• C. A repressible operon is turned on when the repressor protein is not bound to the corepressor molecule.
• D. An active repressor protein is inactivated by the binding of an activator molecule.

Answer: (D)

Verified step by step guidance

1. Understand the concept of an inducible operon: An inducible operon is typically off but can be turned on when an inducer molecule binds to the repressor protein, preventing it from binding to the operator and allowing transcription.
2. Learn about inactive repressor proteins: An inactive repressor protein requires the binding of a corepressor molecule to become active, which then allows it to bind to the operator and inhibit transcription.
3. Explore repressible operons: A repressible operon is usually on but can be turned off when the repressor protein binds to a corepressor molecule, which then binds to the operator to block transcription.
4. Examine the statement about active repressor proteins: An active repressor protein is typically inactivated by the binding of an inducer molecule, not an activator molecule. This is a key point to identify the false statement.
5. Compare the statements: Review each statement and compare them to the known mechanisms of operon regulation to identify which statement does not align with the biological processes described.