Question

When trypsin converts chymotrypsinogen to chymotrypsin, some molecules of chymotrypsin bind to a repressor, which in turn binds to the operator and prevents further transcription of trypsin. To which gene regulation system is this process most similar? A. Transduction B. lac operon C. trp operon D. Lysogenic cycle

Short answer

C. trp operon

Step-by-step solution

- Understand the Question

First, break down the question to understand what is being asked. The question describes a scenario where chymotrypsin binding to a repressor prevents further transcription of trypsin.

- Identify Key Concept

Recognize that this scenario involves gene regulation, specifically negative feedback inhibition where the presence of a product inhibits its own production.

- Compare to Known Systems

Compare each given option (Transduction, lac operon, trp operon, Lysogenic cycle) to find the one with similar regulation mechanism: - Transduction involves gene transfer via bacteriophages, not regulation. - lac operon is inducible and regulated by an inducer, not by end-product inhibition. - trp operon involves a feedback inhibition mechanism similar to the scenario described. - Lysogenic cycle deals with virus integration into host DNA and not relevant for feedback inhibition.

- Choose the Best Answer

Given that trp operon uses a feedback loop for regulating tryptophan synthesis where tryptophan binds to a repressor to inhibit further production, identify it as the most similar to the described process.

Key concepts

Negative Feedback Inhibition

Negative feedback inhibition is a common mechanism in biological systems. It occurs when the end product of a process inhibits the process itself. This mechanism helps maintain balance within biological systems. For instance, in enzyme regulation,
when enough product is made, it binds to the enzyme that produced it and stops further production.
This ensures that cells do not waste resources producing more of a substance than needed.
An example is how chymotrypsin, when bound to a repressor, inhibits the transcription of trypsin. This system ensures that trypsin production is kept in check, avoiding excessive enzyme buildup.

trp Operon

The trp operon is a well-studied example of gene regulation through negative feedback inhibition. Found in bacteria like E. coli, it consists of a group of genes necessary for tryptophan production.
The operon is controlled by a repressor protein that binds to the operator region to block transcription.
When tryptophan levels are high, tryptophan molecules bind to the repressor, which then attaches to the operator, halting production.
This makes sure the cell does not waste energy producing tryptophan when there is already enough available. In low tryptophan conditions, the repressor is inactive, allowing gene transcription.
This feedback loop ensures efficient regulation of tryptophan synthesis, saving cellular resources.

Transcription Regulation

Transcription regulation is essential for controlling gene expression. It allows cells to respond to changes in their environment and adjust their functions accordingly.
This process involves various mechanisms, including repressors and activators that bind to DNA sequences near genes to control their transcription.
For example, the repressor in the trp operon binds to the operator sequence, preventing RNA polymerase from attaching and transcribing the genes.
Alternatively, activators can help RNA polymerase bind to the promoter region, enhancing transcription.
Transcriptional regulation ensures genes are only expressed when needed, aligning gene activity with cellular demands.
This process is critical for maintaining cellular efficiency and adaptability.

Inducible Operons

Inducible operons are genes that are usually turned off but can be switched on in response to specific molecules. A classic example is the lac operon in E. coli, which controls the metabolism of lactose.
This operon remains off unless lactose is present. When lactose is available, it binds to the repressor protein and changes its shape, preventing the repressor from attaching to the operator.
This removal of the repressor allows RNA polymerase to transcribe the genes necessary for lactose metabolism. Inducible operons allow bacteria to adapt to their environment by switching on metabolic pathways only when substrates are available, conserving energy and resources.