Term
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Definition
Third line of defense after physical barriers and innate IR
Main cells involved T and B-cells
Receptors that uniquely bind to a pathogen are selected and then amplified
Only one type of receptor for B-cells (BCR) and only one type for T-cells (TCR)
But each T or B receptor can be specific (bind to) for Millions of different antigens
Each receptor recognizes a different molecular structure |
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Term
| Advantages of Adaptive Immune Response |
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Definition
Having millions of receptors that are able to bind to different antigens means that almost any antigen can be recognized.
An antigen binding site on one B-cell will recognize a different antigen than a second B-cells antigen binding site.
Memory cells are formed from the first encounter, so that after a pathogen has been cleared, if the pathogen is encountered again, it will be cleared very quickly by those memory cells still present.
The memory cells will expand their population to clear the invader.
A way for the slowly evolving vertebrates to recognize the ever changing antigens of the quickly evolving microbes. |
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Term
| Immunoglobulins and T cell Receptors are Variable Recognition Molecules |
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Definition
Igs expressed on B cells -- bind pathogens
Plasma cells (effector B cells) secrete antibodies (Igs)
T cell receptors (TCRs) are not secreted
Antigen (Ag) is any molecule detected by Ig or TCR
Igs and TCRs have specificity for Ags
Epitope (or antigenic determinant) is that part of the antigen bound by Ig or TCR |
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Term
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Definition
Variable and Constant regions
Variable region = binding to antigen
Each BCR will have a different AA sequence in this region
Millions of diff. specificities
Constant region = (antibodies) contain binding sites for phagocytic cells (ex. macrophages) for phagocytosis
AA sequence very similar among Ig’s
Antibodies can act as an adaptor molecule
Different constant regions on antibodies (secreted Ig’s) allow different effector functions |
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