IB Biology Topic C2.1.2 Cell Signalling by Bacteria in Quorum Sensing Revision Notes (HL)

IB Biology Topic C2.1.2 Cell Signalling by Bacteria in Quorum Sensing Revision Notes (HL) | RevisionDojo

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Quorum Sensing: Bacteria Act as a Group Once Their Numbers Are High Enough

Picture a crowded room where everyone whispers.
At first the whispers are too faint to hear.
As more people join in, the combined sound grows loud enough to trigger a response.
This is how quorum sensing works in bacteria: they coordinate their behaviour based on population density.

Definition

Quorum Sensing

A communication system used by bacteria to coordinate group behaviors based on population density through the release and detection of signaling molecules.

How It Works: Signals Build Up Until a Threshold Flips the Whole Group

Signal production
1. Each bacterium constantly releases small chemical signals called autoinducers.
Accumulation
1. As the population grows, the concentration of autoinducers in the surroundings rises.
Detection
1. Once the concentration passes a critical threshold, the autoinducers bind to receptor proteins in the bacteria.
Coordinated response
1. Binding changes gene expression across the population, so the bacteria switch on group behaviours together.

Analogy

Treat autoinducers as text messages sent out by every bacterium.
Only when enough messages pile up does the group decide to act as one.

Aliivibrio fischeri: A Squid Uses Bacterial Light to Hide

Aliivibrio fischeri (formerly Vibrio fischeri) is a marine bacterium that uses quorum sensing to produce light by bioluminescence.
This is seen most clearly in its partnership with the Hawaiian bobtail squid.

Density Decides Whether the Cells Glow

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Quorum Sensing: Bacteria Act as a Group Once Their Numbers Are High Enough

Picture a crowded room where everyone whispers.
At first the whispers are too faint to hear.
As more people join in, the combined sound grows loud enough to trigger a response.
This is how quorum sensing works in bacteria: they coordinate their behaviour based on population density.

Definition

Quorum Sensing

A communication system used by bacteria to coordinate group behaviors based on population density through the release and detection of signaling molecules.

How It Works: Signals Build Up Until a Threshold Flips the Whole Group

Signal production
1. Each bacterium constantly releases small chemical signals called autoinducers.
Accumulation
1. As the population grows, the concentration of autoinducers in the surroundings rises.
Detection
1. Once the concentration passes a critical threshold, the autoinducers bind to receptor proteins in the bacteria.
Coordinated response
1. Binding changes gene expression across the population, so the bacteria switch on group behaviours together.

Analogy

Treat autoinducers as text messages sent out by every bacterium.
Only when enough messages pile up does the group decide to act as one.

Aliivibrio fischeri: A Squid Uses Bacterial Light to Hide

Aliivibrio fischeri (formerly Vibrio fischeri) is a marine bacterium that uses quorum sensing to produce light by bioluminescence.
This is seen most clearly in its partnership with the Hawaiian bobtail squid.

Density Decides Whether the Cells Glow

Definition

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Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic C2.1.2: Cell Signalling by Bacteria in Quorum Sensing Notes

Quorum Sensing: Bacteria Act as a Group Once Their Numbers Are High Enough

How It Works: Signals Build Up Until a Threshold Flips the Whole Group

Aliivibrio fischeri: A Squid Uses Bacterial Light to Hide

Density Decides Whether the Cells Glow

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Quorum Sensing: Bacteria Act as a Group Once Their Numbers Are High Enough

How It Works: Signals Build Up Until a Threshold Flips the Whole Group

Aliivibrio fischeri: A Squid Uses Bacterial Light to Hide

Density Decides Whether the Cells Glow

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics