Question

In bacteria, the a fuctor that plays a major role in transcription during the stationary phase is

• A. \(\sigma^{70}\)
• B. \(\sigma^{54}\)
• C. \(\sigma^{28}\)
• D. \(\sigma^{38}\)

Answer 1

The Correct Option is D

The question is about identifying the σ factor in bacteria that plays a major role in transcription during the stationary phase. Let's analyze the options and understand which σ factor is correct:

In bacteria, the σ factors are proteins that are crucial for the initiation of transcription. Each σ factor recognizes specific promoter sequences and directs the RNA polymerase to start the transcription process.

1. \(\sigma^{70}\): This is the primary sigma factor in many bacteria, including Escherichia coli, responsible for most of the gene expression during the exponential growth phase.
2. \(\sigma^{54}\): This sigma factor is involved in the expression of genes related to nitrogen metabolism and is also known for its role in surviving under specific nutritional conditions.
3. \(\sigma^{28}\): This σ factor is involved in the expression of flagellar and chemotaxis genes, primarily significant under conditions that necessitate bacterial motility.
4. \(\sigma^{38}\): Known as the sigma factor for the stationary phase, it is also referred to as the stress response σ factor, because it is upregulated and becomes important when bacteria enter the stationary phase, signaling a need to respond to nutrient depletion, high cell density, or environmental stress.

Based on the roles described, \(\sigma^{38}\) is the sigma factor that plays a major role during the stationary phase of bacterial growth. It helps in turning on the genes necessary for survival in tough conditions, making it the correct answer.

Conclusion: The correct answer is \(\sigma^{38}\), which is specific for the stationary phase in bacteria.