Immune System
Numerous antibodies can be prepared, against one antigen, each binds to unique epitopes. How is this antibody diversity generated?

Antibody proteins can physically change their shape to bind different epitopes
By the combination of different heavy and light chains that form the antigen binding site
By rearrangements of the DNA encoding the variable regions of the heavy and light chains
Both (a) and (b)

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Immune System
Polymorphonuclear leukocytes (or PMNs)

All of these
are derived from bone marrow stem cells
can be attracted to the site of an infection following activation of complement
are a type of phagocyte that can engulf and kill bacteria

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