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Questions and Answers
Binding of attractant inhibits receptor function and decreases CheY ______, reducing tumbling instantaneously.
Binding of attractant inhibits receptor function and decreases CheY ______, reducing tumbling instantaneously.
phosphorylation
Bacterial movement is driven by CCW rotation of the flagella, while tumbling is the result of motor reversal and ______ rotation of the flagella.
Bacterial movement is driven by CCW rotation of the flagella, while tumbling is the result of motor reversal and ______ rotation of the flagella.
CW
Increasing attractant concentrations increase the probability to continue moving in the direction of the attractant via a suppression of ______.
Increasing attractant concentrations increase the probability to continue moving in the direction of the attractant via a suppression of ______.
tumbling
Adaptation involves increased methylation at a slower rate through activation of the demethylase ______.
Adaptation involves increased methylation at a slower rate through activation of the demethylase ______.
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Chemotactic movement of Dictyostelium cells to cyclic AMP involves persistent extension of ______ in the direction of the signal.
Chemotactic movement of Dictyostelium cells to cyclic AMP involves persistent extension of ______ in the direction of the signal.
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Cells move by extending two pseudopods at the front of the cell in a random ______.
Cells move by extending two pseudopods at the front of the cell in a random ______.
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Bacterial aggregation patterns in E coli cultures can produce complex spatio-temporal ______.
Bacterial aggregation patterns in E coli cultures can produce complex spatio-temporal ______.
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The ______ in aggregation competent Dictyostelium discoideum leads to chemotaxis and signal amplification.
The ______ in aggregation competent Dictyostelium discoideum leads to chemotaxis and signal amplification.
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CAMP triggering at the aggregation center results in nearby cells relaying the cAMP ______.
CAMP triggering at the aggregation center results in nearby cells relaying the cAMP ______.
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In bacterial chemotaxis, phosphorylation of ______ plays a key role in the signaling pathway.
In bacterial chemotaxis, phosphorylation of ______ plays a key role in the signaling pathway.
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Methylation of CheR and CheB receptors helps with ______ in bacterial chemotaxis.
Methylation of CheR and CheB receptors helps with ______ in bacterial chemotaxis.
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Flagella rotation in bacteria is influenced by the ______ state of CheY.
Flagella rotation in bacteria is influenced by the ______ state of CheY.
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Actin polymerisation and Myosin filament assembly contribute to cell ______ in chemotaxis.
Actin polymerisation and Myosin filament assembly contribute to cell ______ in chemotaxis.
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Bacterial chemotaxis involves ______ sensing.
Bacterial chemotaxis involves ______ sensing.
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______ phosphorylation is a key process in bacterial chemotaxis.
______ phosphorylation is a key process in bacterial chemotaxis.
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In eukaryotic chemotaxis, cells detect ______ gradients.
In eukaryotic chemotaxis, cells detect ______ gradients.
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Methylation and ______ are essential for adaptation in bacterial chemotaxis.
Methylation and ______ are essential for adaptation in bacterial chemotaxis.
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The rotation of ______ is coupled with the phosphorylation state of CheY in bacteria.
The rotation of ______ is coupled with the phosphorylation state of CheY in bacteria.
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Dictyostelium development is controlled by propagating waves of ______.
Dictyostelium development is controlled by propagating waves of ______.
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Chemotactic movement in Dictyostelium is modeled through a flow in an ______ liquid.
Chemotactic movement in Dictyostelium is modeled through a flow in an ______ liquid.
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The chemotactic force in Dictyostelium is proportional to the gradient of ______.
The chemotactic force in Dictyostelium is proportional to the gradient of ______.
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What is the primary effect of attractant binding on CheY phosphorylation?
What is the primary effect of attractant binding on CheY phosphorylation?
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How does increasing attractant concentrations influence bacterial movement?
How does increasing attractant concentrations influence bacterial movement?
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What role does adaptation through demethylase CheB play in bacterial chemotaxis?
What role does adaptation through demethylase CheB play in bacterial chemotaxis?
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What mechanism drives amoeboid cell movement?
What mechanism drives amoeboid cell movement?
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What describes the movement pattern of bacteria in the presence of attractants or repellents?
What describes the movement pattern of bacteria in the presence of attractants or repellents?
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What is the role of PTEN in the chemotaxis signaling pathway of Dictyostelium?
What is the role of PTEN in the chemotaxis signaling pathway of Dictyostelium?
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Which molecule is primarily involved in the directional movement of cells during chemotaxis?
Which molecule is primarily involved in the directional movement of cells during chemotaxis?
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What kind of gradient do hemotaxing eukaryotic cells measure to facilitate movement?
What kind of gradient do hemotaxing eukaryotic cells measure to facilitate movement?
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In the chemotaxis signaling pathway, what effect does the activation of PI3 kinase have?
In the chemotaxis signaling pathway, what effect does the activation of PI3 kinase have?
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How does the activity of Rac GEF contribute to the signaling pathway in Dictyostelium?
How does the activity of Rac GEF contribute to the signaling pathway in Dictyostelium?
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Which model describes the pattern formation within chemotactic cells?
Which model describes the pattern formation within chemotactic cells?
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What is the significance of the GRP1-PH domain-GFP sensor in investigating chemotaxis?
What is the significance of the GRP1-PH domain-GFP sensor in investigating chemotaxis?
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Which of the following factors contributes to cell cortex polarisation during chemotaxis?
Which of the following factors contributes to cell cortex polarisation during chemotaxis?
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What is the primary mechanism of bacterial movement in finding food?
What is the primary mechanism of bacterial movement in finding food?
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How does increasing attractant concentrations affect the movement of bacteria?
How does increasing attractant concentrations affect the movement of bacteria?
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What role does the CheA kinase play in bacterial chemotaxis?
What role does the CheA kinase play in bacterial chemotaxis?
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What effect does the binding of attractants have on CheB activity?
What effect does the binding of attractants have on CheB activity?
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What happens to the frequency of tumbling when a bacterium is exposed to higher levels of chemo-attractant?
What happens to the frequency of tumbling when a bacterium is exposed to higher levels of chemo-attractant?
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What is a significant feature of the mean square displacement in diffusion?
What is a significant feature of the mean square displacement in diffusion?
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Which direction of flagellar rotation is associated with a 'run' in bacterial movement?
Which direction of flagellar rotation is associated with a 'run' in bacterial movement?
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What effect does increased methylation have on the bacterial receptor function?
What effect does increased methylation have on the bacterial receptor function?
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What initiates the movement of bacterial cells towards an attractant in E. coli cultures?
What initiates the movement of bacterial cells towards an attractant in E. coli cultures?
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What is the primary mechanism by which Dictyostelium discoideum cells signal each other during aggregation?
What is the primary mechanism by which Dictyostelium discoideum cells signal each other during aggregation?
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In the context of chemotaxis, what occurs when a pseudopod is extended in the wrong direction?
In the context of chemotaxis, what occurs when a pseudopod is extended in the wrong direction?
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What key process is involved in the amplification of the cAMP signal during Dictyostelium aggregation?
What key process is involved in the amplification of the cAMP signal during Dictyostelium aggregation?
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Which of the following best describes the purpose of cAMP wave propagation in Dictyostelium discoideum?
Which of the following best describes the purpose of cAMP wave propagation in Dictyostelium discoideum?
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In the simulation of cell movement, what determines the persistence of the direction in which a pseudopod extends?
In the simulation of cell movement, what determines the persistence of the direction in which a pseudopod extends?
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What effect does the secretion of an attractant by bacterial populations have on their movement patterns?
What effect does the secretion of an attractant by bacterial populations have on their movement patterns?
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Which process helps cells adapt to changing concentrations of cAMP during Dictyostelium aggregation?
Which process helps cells adapt to changing concentrations of cAMP during Dictyostelium aggregation?
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What mathematical concept is described by the Fitz Hugh-Nagumo equations in relation to cell communication in Dictyostelium?
What mathematical concept is described by the Fitz Hugh-Nagumo equations in relation to cell communication in Dictyostelium?
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Which factor influences the chemotactic force experienced by Dictyostelium cells?
Which factor influences the chemotactic force experienced by Dictyostelium cells?
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How is cell movement described in the context of Dictyostelium development?
How is cell movement described in the context of Dictyostelium development?
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What is a primary characteristic of the aggregation process in Dictyostelium?
What is a primary characteristic of the aggregation process in Dictyostelium?
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What role does adaptation play in the chemotactic behavior of Dictyostelium cells?
What role does adaptation play in the chemotactic behavior of Dictyostelium cells?
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In the continuous model of Dictyostelium development, what does the variable 'g' primarily represent?
In the continuous model of Dictyostelium development, what does the variable 'g' primarily represent?
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Which aspect differentiates eukaryotic chemotaxis from bacterial chemotaxis as outlined in the content?
Which aspect differentiates eukaryotic chemotaxis from bacterial chemotaxis as outlined in the content?
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What kind of patterns emerge from aggregation in Dictyostelium, and what do they represent?
What kind of patterns emerge from aggregation in Dictyostelium, and what do they represent?
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Study Notes
Spatio-temporal Mechanisms Underlying Pattern Formation
- Pattern formation is driven by spatio-temporal mechanisms.
- Systems Biology II is the subject area.
- Kees Weijer is the lecturer.
Diffusion-Random Walk (Brownian Motion)
- Diffusion equation: ∂c/∂t = D(∂²c/∂x²)
- Mean square displacement (MSD) is proportional to time (2Dt).
- MSD is related to the time steps taken and the step length.
Two Dimensional Random Walks
- Diffusion of molecules (Brownian motion).
- Random walks, showing movement in all directions.
- Biased random walks show movement in a specific direction.
Bacterial Movement (Run and Tumble)
- Movement in absence of chemical attractants creates a random walk.
- Movement in presence of chemical attractants creates a biased random walk.
- Run and tumble behaviors are characteristic of bacterial movement.
Bacterial Chemotaxis, Finding Food
- Bacteria move towards attractants and away from repellents.
- A mechanism that uses a biased random walk is used for this.
- The chance of continuously moving in an attractive direction increases with attractant concentration.
- A biased random walk is used with different run lengths.
Chemo-attractants Control Bacterial Flagellar Rotation
- Chemoreceptors and related proteins (Che proteins) guide flagellar rotation.
- Counter-clockwise (CCW) rotation leads to runs; clockwise (CW) rotation leads to tumbles.
- Chemo-attractants modulate flagellar rotation through processes involving protein phosphorylation.
Chemotaxis System of E. coli
- Bacteria swim towards attractants and away from repellents, modulating their tumbling frequency by adding/removing chemo-attractants.
- Attractants rapidly switch CheA kinase off, suppressing tumbling.
- The chemoreceptor's methylation level by CheR and CheB determines its activation level.
- Binding of attractant instantaneously decreases CheY phosphorylation and reduces tumbling.
- Increased methylation leads to increased CheY phosphorylation and increased tumbling
Bacterial Movement and Chemotaxis
- Bacterial movement is driven by CCW flagellar rotation.
- Bacteria either move towards an attractant or away from a repellent.
- Increasing attractant concentration increases movement in that direction, suppressing tumbling.
- Adaptation changes the tumbling frequency, which modifies direction towards stimulus
Amoeboid Cell Movement
- Driven by actin polymerization at the leading edge and myosin II driven retraction at the rear.
- Steps in the cell cycle are extension, attachment, and contraction.
Moving Amoeba and Random Walk
- Amoebas extend and retract cellular protrusions randomly in the absence of direction signals.
- This results in a random walk.
Chemotactic Movement of Dictyostelium cells to Cyclic AMP
- Dictyostelium cells move persistently towards the direction of the cyclic AMP signal.
- Cells polarize or align and move directionally.
Chemotaxis Signalling Pathways in Dictyostelium
- Signaling pathways involve proteins, kinases, and GTP/GTP interactions/activities.
- Signaling leads to actin polymerization triggering pseudopod extension.
PI(3,4,5)P3 (GRP1-PH domain-GFP sensor)
- A specific molecule.
PTEN-GFP Localization in Back of Cell
- Specific localization of the PTEN protein.
Models for Pattern Formation
- Turing (1952) and Gierer & Meinhardt (1982) models describe pattern formation based on reaction-diffusion systems.
Pattern Formation in 1&2D
- Gradient and wave formation.
- Stripe and cell cortex polarisation are mentioned as types of patterning.
Eukaryotic Cell Chemotaxis to Measure Gradients
- Eukaryotic cells measure gradients along their length and amplify the signal for directional movement.
Bacterial Aggregation Patterns in E. coli Cultures
- Bacteria produce and secrete attractants, resulting in complex spatio-temporal patterns in growing cultures.
Dictyostelium Discoideum Life Cycle
- Dictyostelium has a life cycle showing spore germination, vegetative cells and aggregation, streams and darkfield waves, mounds and movement to fruiting body
cAMP to cAMP Receptors in Aggregation Competent Dictyostelium
- cAMP binding to the receptors triggers two responses: chemotaxis and cAMP signal amplification.
cAMP Wave Propagation in Dictyostelium Discoideum
- cAMP waves propagate in the aggregation process.
cAMP Waves Control Chemotactic Movement
- cAMP waves control the chemotactic movement of thousands of cells.
Multicellular Dictyostelium Development
- Multicellular development is controlled by propagating waves of the chemoattractant cAMP.
Continuous Model for Dictyostelium Development
- Describes mathematical models for the cell's behavior and their interaction in an aggregation process.
Mathematical Modelling of Aggregation, Mound Formation, and Slug Migration
- Describes mathematical models for aggregation, mound formation, and slug migration
Wildtype Aggregation and cAMP Relay Mutant
- Differences in aggregation behavior between wildtype and mutant Dictyostelium cells.
cAMP Waves Directing Chemotaxis
- Cyclic AMP waves direct chemotaxis and control the morphogenesis of the Dictyostelium aggregation process.
Spatio-temporal Pattern Formation
- Bacterial chemotaxis uses temporal sensing, and eukaryotic chemotaxis uses spatial gradient sensing.
- Pattern formation is driven by non-linear reaction dynamics (activator and inhibitor interactions).
- Interactions between signaling and movement produce complex patterns, critical in development.
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Description
Test your knowledge on the mechanisms of bacterial movement and chemotaxis. This quiz covers key concepts such as receptor function, flagella rotation, and the role of chemotactic signals. Explore how attractant concentrations and methylation influence directional movement.
