9700 · 11.2
Antibodies and vaccination flashcards
Revision flashcards for Cambridge 9700 Antibodies and vaccination (syllabus 11.2). Flip, recall, then mark a real past-paper question.
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What are the four polypeptide chains in an antibody?
Two identical heavy chains and two identical light chains, linked by disulfide bonds into a Y-shape.
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Where is the antigen-binding site located?
On the variable regions at the tips of the two arms of the Y-shaped antibody molecule.
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Define active immunity.
Immunity produced when the body makes its own antibodies and memory cells after exposure to an antigen; long-lasting.
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Define passive immunity.
Immunity from receiving pre-formed antibodies; immediate but short-term with no memory cell formation.
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What is a vaccine?
A preparation containing antigens (live attenuated, killed, toxoid, or subunit) used to stimulate artificial active immunity safely.
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How does vaccination lead to memory cells?
APCs present antigen to T helper cells, which activate B cells; clonal selection and expansion produce plasma cells and memory B cells.
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What is herd immunity?
When a high proportion of a population is immune, reducing pathogen spread and protecting non-immune individuals.
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Name two functions of antibodies.
Agglutination of pathogens, neutralisation of toxins, opsonisation for phagocytosis, or precipitation of antigens.