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Questions and Answers
What are regulons characterized by?
What are regulons characterized by?
Which regulatory protein is involved in the SOS response by cleaving lexA?
Which regulatory protein is involved in the SOS response by cleaving lexA?
What does catabolite repression primarily do?
What does catabolite repression primarily do?
What role does the sigma factor play in bacterial transcription?
What role does the sigma factor play in bacterial transcription?
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When is the SOS response typically activated?
When is the SOS response typically activated?
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What is the function of lexA in the SOS response?
What is the function of lexA in the SOS response?
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Which sigma factor is commonly associated with heat response in bacteria?
Which sigma factor is commonly associated with heat response in bacteria?
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What happens once the damage has been repaired in the SOS response?
What happens once the damage has been repaired in the SOS response?
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What is the primary function of quorum sensing in microbial communication?
What is the primary function of quorum sensing in microbial communication?
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In the context of quorum sensing, what role do autoinducer molecules play?
In the context of quorum sensing, what role do autoinducer molecules play?
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How does the Hawaiian bobtail squid utilize quorum sensing?
How does the Hawaiian bobtail squid utilize quorum sensing?
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What distinguishes the V. fischeri cells when they are in the light organ of the squid?
What distinguishes the V. fischeri cells when they are in the light organ of the squid?
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Which of the following is NOT a characteristic of quorum sensing?
Which of the following is NOT a characteristic of quorum sensing?
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What is the primary function of the operator site in DNA with regard to transcription?
What is the primary function of the operator site in DNA with regard to transcription?
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Which type of enzymes is primarily controlled by repression during negative control?
Which type of enzymes is primarily controlled by repression during negative control?
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How does induction affect transcription?
How does induction affect transcription?
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What is the role of co-repressor in repression?
What is the role of co-repressor in repression?
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What mechanism is involved in the positive control of transcription?
What mechanism is involved in the positive control of transcription?
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What is typically the result when a signal inhibits transcription through repression?
What is typically the result when a signal inhibits transcription through repression?
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In the context of negative control, what does 'derepression' mean?
In the context of negative control, what does 'derepression' mean?
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Which of the following describes the role of the allosteric protein in the positive control mechanism?
Which of the following describes the role of the allosteric protein in the positive control mechanism?
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What does a high level of glucose detection indicate about its transport?
What does a high level of glucose detection indicate about its transport?
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What role does tryptophan play in the tryptophan synthesis operon?
What role does tryptophan play in the tryptophan synthesis operon?
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In the context of the tryptophan synthesis operon, what is the significance of negative control?
In the context of the tryptophan synthesis operon, what is the significance of negative control?
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Which mechanism describes how rho-dependent termination occurs in bacterial transcription?
Which mechanism describes how rho-dependent termination occurs in bacterial transcription?
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What is the key characteristic of rho-independent termination?
What is the key characteristic of rho-independent termination?
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Which structural genes in the tryptophan operon are necessary for synthesizing tryptophan?
Which structural genes in the tryptophan operon are necessary for synthesizing tryptophan?
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How does attenuation affect transcription regulation?
How does attenuation affect transcription regulation?
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What is the role of RNA polymerase during transcription in bacteria?
What is the role of RNA polymerase during transcription in bacteria?
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What effect does phosphorylated CheY have on flagellar movement?
What effect does phosphorylated CheY have on flagellar movement?
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What happens in the absence of attractants in terms of CheA activity?
What happens in the absence of attractants in terms of CheA activity?
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Which protein is responsible for demethylation of MCPs?
Which protein is responsible for demethylation of MCPs?
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What is the role of MCPs in the adaptation response?
What is the role of MCPs in the adaptation response?
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What happens to the sensitivity of MCPs when moving away from a repellent?
What happens to the sensitivity of MCPs when moving away from a repellent?
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How does CheZ contribute to the system after tumbling occurs?
How does CheZ contribute to the system after tumbling occurs?
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What is a feedback loop in the context of MCPs and their adaptation?
What is a feedback loop in the context of MCPs and their adaptation?
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What determines the direction of flagellar rotation in a 'bad' situation?
What determines the direction of flagellar rotation in a 'bad' situation?
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Which of the following statements about Che proteins is true?
Which of the following statements about Che proteins is true?
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What is the primary function of constitutive genes?
What is the primary function of constitutive genes?
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How do covalent modifications regulate protein activity?
How do covalent modifications regulate protein activity?
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What does allosteric regulation involve?
What does allosteric regulation involve?
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Why is energy conservation important in regulating transcription?
Why is energy conservation important in regulating transcription?
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What are inducible genes characterized by?
What are inducible genes characterized by?
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Which of the following is a key characteristic of the Operon?
Which of the following is a key characteristic of the Operon?
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What role do key cellular enzymes play in metabolism?
What role do key cellular enzymes play in metabolism?
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What is the impact of changes in environmental conditions on gene regulation?
What is the impact of changes in environmental conditions on gene regulation?
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Which is NOT a method of regulating protein activity?
Which is NOT a method of regulating protein activity?
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What is a potential consequence of not turning off certain cellular processes?
What is a potential consequence of not turning off certain cellular processes?
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Study Notes
DNA Regulation
- DNA must be copied to create new cells
- Transcription converts DNA into working copies for enzymes and structural proteins
- Not all processes run simultaneously; cell regulation prevents unnecessary functions and cell death
Environmental Conditions
- Environmental factors like nutrient availability and competition affect gene regulation
- Cells respond to changes in conditions through specific responses
- Substrate specificity and metabolism are regulated by environment
Key Cellular Enzymes
- Constitutive enzymes are always active, preventing cell death
- Examples include those involved in TCA cycle and ATP synthesis
- Constitutive genes are housekeeping genes, always expressed
Covalent Modification
- Enzymes' activity is altered by adding or modifying amino acids
- Methods include phosphorylation, acetylation, methylation, and glycosylation
- Conformation changes affect active sites and influence enzyme activity
Allosteric Regulation
- Small molecules interact with an allosteric site, changing enzyme conformation
- This might lead to activation (better fit to the substrate) or inhibition (worse fit) of the active site
- Results from an interaction that is not directly at the active site
Regulating Transcription
- Energy is conserved through controlling enzyme synthesis to prevent transcription of unnecessary genes
- The operon, a collection of structural and regulatory elements, controls structural gene expression.
Positive Control
- A regulatory protein will enhance RNA polymerase binding to the promoter, increasing transcription.
- RNA polymerase and sigma factor don't bind, activator proteins will help bind
Negative Control
- Transcription is inhibited by regulatory proteins that block RNA polymerase processes
- Two types: repression (stopping transcription already in progress) and induction (preventing transcription altogether).
Operon Structure and Control
- Structural genes are grouped together under one regulatory system.
- Promoter: DNA sequence where RNA polymerase binds.
- Operator: DNA sequence where a repressor protein can bind to prevent transcription.
Positive and Negative Control Regulation
- Positive control uses a regulatory protein to enhance the binding of RNA polymerase to the promoter for increased transcription expression.
- Negative control utilizes a regulatory protein to prevent RNA polymerase from binding to the promoter, decreasing transcription
Genes and Operons
- The lac operon regulates lactose metabolism, switching on expression when glucose is depleted.
- Lactose is better to use than glucose (easier/cheaper) as an energy source
- Use of lactose expression occurs when glucose is not available, thus transcription occurs to get it in and break it down
Attenuation
- Transcription can be stopped before termination (transcription is halted before it is completed)
- Rho-dependent and rho-independent mechanisms are used to end transcription
- Ribosomes' presence impacts transcription to ensure genes will only be expressed when required
Tryptophan Synthesizing Regulation
- Genes for tryptophan synthesis are regulated, preventing unnecessary production
- Attenuation controls tryptophan production based on current levels.
Positive and Negative Control of Transcription
- Transcription can be either enhanced or suppressed by effector molecules (a chemical/signal) binding to DNA binding proteins.
Quorum Sensing
- Bacteria communicate with each other through chemical signals, quorum sensing, to coordinate population density-dependent actions.
- Cells release molecules based on population density to regulate gene expression
Hawaiian Bobtail Squid Bioluminescence
- Bioluminescence (light production) is regulated to conserve energy
- N-acyl-homoserine lactone (AHL) regulates it in specific amounts.
No Quorum
- Lux genes, when they function poorly, do not produce as much light
- Enzyme (luxI) is present. It produces AHL during the day.
- The activator protein isn't present thus light is not produced/ made
Chemotaxis
- Bacteria's response to chemical gradients is chemotaxis.
- They use chemotaxis proteins to sense chemical gradients to control how they respond to and move toward or away from attractant and repellents
Adaptation
- Chemotaxis adaptation regulates sensitivity to attractants and repellents based on methylation of certain proteins.
- Methylation/demethylation changes the sensitivity to attractants/repellents
Two-component regulatory systems
- The system includes a sensor kinase, which detects stimuli
- Histidine protein kinases are sensor kinases which add phosphate groups to proteins (phosphate group is a signal)
- The response regulators regulate transcription based on the signal from the sensory kinase.
Two-Component regulatory systems (additional details)
- Stimulus outside the cell is detected by sensor proteins (sensor kinase) (HPK)
- Phosphate group is transferred to the regulator (response) (RR)
- The regulator controls the gene transcription response to stimulus (short lived response)
- Re-establishing the original state of the response is crucial for regulating the process
- Examples include crown gall tumors, and plant bacterial interactions
Other Considerations
- alternative sigma factors control transcription when the default sigma factor isn't suitable (for instance, in heat, stress, etc.)
- Regulons are sets of genes coordinately controlled by a single regulatory system for coordinated expression/ action
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Description
This quiz covers the essential concepts of DNA regulation, including transcription, the influence of environmental conditions on gene expression, and the role of key cellular enzymes. Explore the different mechanisms of enzyme regulation, such as covalent modification and allosteric regulation, to understand cellular function better.