IB Biology Topic C3.2.9: Multiplication of Activated B-lymphocytes Notes

Clonal expansion turns a few activated B-cells into a large clone

Only a small number of B-cells recognise any given pathogen at first.

Once one of these B-cells is activated (see C3.2.8), it begins to divide.

This division into many identical copies is called clonal expansion.

Analogy

One firefighter cannot put out a large fire alone.
Calling in a whole team can, and clonal expansion scales up B-cells the same way.

Expansion is needed because each B-cell is specific and starts rare

Each B-cell is highly specific and recognises only one antigen.

So only a few cells can respond to a new pathogen at the start.

Clearing the pathogen needs millions of antibodies, which means a large population of plasma cells.

Pathogens multiply quickly, so the response must scale up fast.

Note

Clonal expansion is the emergency scale-up that matches antibody output to the size of the threat.

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IB Biology Topic C3.2.9: Multiplication of Activated B-lymphocytes Notes

Clonal expansion turns a few activated B-cells into a large clone

Expansion is needed because each B-cell is specific and starts rare

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

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Clonal expansion turns a few activated B-cells into a large clone

Expansion is needed because each B-cell is specific and starts rare

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

IB Biology Topic C3.2.9: Multiplication of Activated B-lymphocytes Notes

Clonal expansion turns a few activated B-cells into a large clone

Expansion is needed because each B-cell is specific and starts rare

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

Clonal expansion turns a few activated B-cells into a large clone

Expansion is needed because each B-cell is specific and starts rare

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