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Multiple Choice
Which type of operon is typically represented by a system that is normally 'off' but can be turned 'on' in the presence of a specific substrate, as illustrated in Model 1?
A
Attenuated operon
B
Inducible operon
C
Repressible operon
D
Constitutive operon
Verified step by step guidance
1
Understand the concept of an operon: An operon is a cluster of genes under the control of a single promoter and regulatory elements, allowing coordinated expression of genes involved in a specific function.
Learn about the types of operons: Operons can be classified as inducible, repressible, constitutive, or attenuated based on their regulatory mechanisms.
Focus on inducible operons: These operons are normally 'off' because their repressor protein binds to the operator region, preventing transcription. They can be turned 'on' when a specific substrate (inducer) binds to the repressor, causing it to detach from the operator and allowing transcription to proceed.
Compare with other operon types: Repressible operons are typically 'on' but can be turned 'off' when a specific molecule (corepressor) binds to the repressor. Constitutive operons are always 'on' and are not regulated. Attenuated operons involve regulation through transcription termination mechanisms.
Apply the concept to the question: The system described in the problem is normally 'off' but can be turned 'on' in the presence of a specific substrate, which matches the definition of an inducible operon.