II. Sensing and Signal Transduction Flashcards
(38 cards)
What are the two parts of most signal transduction systems in prokaryotes?
The two parts are the sensor kinase and the response regulator protein.
What is the function of the sensor kinase?
The sensor kinase detects environmental signals and phosphorylates itself.
They are also called histidine kinases due to the histidine residue involved in the phosphorylation.
What is the function of the response regulator protein?
The response regulator protein receives the phosphate group from the sensor kinase and mediates the cellular response.
Why do two-component regulatory systems require a feedback loop?
Feedback loops are necessary to ensure that the response is appropriately regulated and can be turned off when the signal is no longer present.
How are phosphatases involved in feedback loops?
Phosphatases dephosphorylate the response regulator, helping to reset the system.
What are three key examples of two-component systems found in Bacteria and Archaea?
Examples include the EnvZ/OmpR system, the PhoR/PhoB system, and the CheA/CheY system.
What is the function of the EnvZ protein in E. coli’s osmolarity detection system?
EnvZ is a sensor kinase that detects changes in osmolarity.
What is the function of the OmpR protein in E. coli’s osmolarity detection system?
OmpR is a response regulator that controls the expression of porin genes.
What is the role of the ompF gene in E. coli’s osmolarity detection system?
The ompF gene encodes a porin that allows the passage of small molecules when osmotic pressure is low.
What is the role of the ompC gene in E. coli’s osmolarity detection system?
The ompC gene encodes a porin that is expressed when osmotic pressure is high.
Which type of porin is produced when osmotic pressure is low?
The ompF porin is produced when osmotic pressure is low.
Which type of porin is produced when osmotic pressure is high?
The ompC porin is produced when osmotic pressure is high.
How do eukaryotic two-component regulatory systems differ from those in prokaryotes?
Eukaryotic systems often involve more complex signaling pathways and multiple layers of regulation.
What is quorum sensing?
Quorum sensing is a process by which bacteria communicate and coordinate behavior based on population density.
What is an autoinducer?
An autoinducer is a signaling molecule used in quorum sensing to trigger gene expression.
How do autoinducers trigger the transcription of specific genes?
Autoinducers can either bind to receptors on the cell surface or enter the cell and bind to intracellular receptors.
What are acyl homoserine lactones (AHLs)?
AHLs are a type of autoinducer produced by many Gram-negative bacteria.
What is autoinducer 2 (AI-2)?
AI-2 is a universal autoinducer used by both Gram-positive and Gram-negative bacteria, differing from AHLs in its production and function.
What do gram positive cells typically use as autoinducers?
Gram positive cells typically use peptides as autoinducers.
How is quorum sensing used to regulate the emission of light by Aliivibrio fischeri?
Quorum sensing allows Aliivibrio fischeri to coordinate light production when a sufficient population density is reached.
What are two examples of how quorum sensing is used in fungi?
Quorum sensing in fungi regulates spore formation and the production of secondary metabolites.
What is unique about the regulation of virulence genes in E. coli O157:H7?
The regulation of virulence genes is tightly controlled by quorum sensing and environmental signals.
How is quorum sensing used to regulate the expression of virulence genes in S. aureus?
Quorum sensing in S. aureus regulates virulence gene expression based on population density and the presence of autoinducers.
What is the stringent response?
The stringent response is a regulatory mechanism that helps bacteria adapt to stress conditions by altering gene expression.
