In lac operon, transcription is inhibited by binding into ?
**Core Concept**
The lac operon is a well-studied example of gene regulation in prokaryotes, specifically in the bacterium Escherichia coli (E. coli). It is a genetic switch that controls the expression of genes involved in lactose metabolism. The lac operon is a classic example of negative gene regulation, where the binding of a repressor protein inhibits the transcription of the target genes.
**Why the Correct Answer is Right**
In the lac operon, the lac repressor protein is responsible for inhibiting transcription. The lac repressor is a tetrameric protein that binds to the operator region of the lac operon. This binding prevents the RNA polymerase from transcribing the genes involved in lactose metabolism. The lac repressor is a classic example of a repressor protein that binds to the operator region of an operon to inhibit transcription. The lac repressor is encoded by the lacI gene and is responsible for regulating the expression of the lac operon in response to the presence of lactose in the environment.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not correct because the lac repressor is a specific protein that binds to the operator region of the lac operon, whereas this option does not specify a protein or a region.
* **Option B:** This option is not correct because the lac repressor is a specific protein that binds to the operator region of the lac operon, whereas this option suggests a general mechanism of gene regulation that is not specific to the lac operon.
* **Option D:** This option is not correct because the lac repressor is a specific protein that binds to the operator region of the lac operon, whereas this option suggests a different type of regulatory mechanism.
**Clinical Pearl / High-Yield Fact**
The lac operon is a classic example of negative gene regulation, where the binding of a repressor protein inhibits the transcription of the target genes. This regulatory mechanism is essential for controlling the expression of genes involved in lactose metabolism in E. coli. Understanding the lac operon is crucial for appreciating the complex mechanisms of gene regulation in prokaryotes.
**Correct Answer:** C.