Prokaryotic_transcriptional_regulation

What is transcriptional regulation in prokaryotes responsible for?

It controls cellular state, mRNA levels of genes, and thereby protein levels in the cell.

What is the function of sigma factor in prokaryotic transcription?

Sigma factor is required for RNA polymerase to initiate transcription by binding to promoter regions.

What are the two major types of proteins involved in transcription regulation?

Activator proteins, which promote transcription, and repressor proteins, which inhibit transcription.

What sequence is recognized by sigma factor 70 in prokaryotes?

The minus 10 and minus 35 regions of the promoter region.

What is the difference between rho-independent and rho-dependent termination of transcription?

Rho-independent termination involves a hairpin structure in the mRNA, while rho-dependent termination involves the binding of the Rho helicase to the rut site.

What is the lac operon responsible for?

The lac operon is responsible for the breakdown of lactose in bacterial cells.

How does allolactose affect the lac operon?

Allolactose binds to the lac repressor, inactivating it and allowing transcription of the lac operon.

What is the role of cyclic AMP in the regulation of the lac operon?

Cyclic AMP binds to the CAP protein, which helps recruit RNA polymerase to the promoter when glucose levels are low.

What happens to the lac operon when glucose is high and lactose is present?

The lac repressor is not bound to the operator, allowing low-level transcription of the lac operon due to the presence of glucose.

What is the role of AraC in the arabinose operon?

AraC acts as both an activator when arabinose is present and a repressor when it is absent, regulating transcription.

What is the function of the trp operon?

The trp operon is involved in the biosynthesis of tryptophan in bacteria.

How does the presence of tryptophan affect the trp operon?

High levels of tryptophan activate the trp repressor, which binds to the operator and prevents transcription.

What is the significance of the attenuator sequence in the trp operon?

It determines whether transcription should be terminated early or allowed to continue based on tryptophan levels.

What happens when tryptophan levels are low in the trp operon?

The ribosome stalls at tryptophan codons, allowing transcription to continue through the structural genes.

What is the difference between transacting and cisacting factors in the regulation of the lac operon?

Transacting factors are proteins (like the lac repressor) that regulate gene expression, while cisacting factors are DNA sequences (like the operator) that are recognized by these proteins.