Immunity Flashcards
All 6 cards in this deck
What is an antigen?
A molecule (usually a protein) on the surface of a pathogen or cell that is recognised as foreign by the immune system.
What is an antibody and which cells produce it?
A protein that binds to a specific antigen, marking the pathogen for destruction; produced by lymphocytes (white blood cells).
True or false? One type of antibody can bind to any type of antigen.
False. Each antibody is specific — its shape is complementary to one antigen only.
What are memory lymphocytes and what do they do?
Lymphocytes that stay in the blood after an infection; if the same antigen returns they rapidly produce large amounts of antibody.
On a graph of antibody concentration against time, what two features show the secondary response to the same antigen?
Antibodies are produced sooner (shorter delay) and reach a much higher concentration than in the primary response.
What are the steps of the specific immune response?
e.g. a bacterium enters the blood
- Exposure to the pathogen: lymphocytes recognise its antigens as foreign.
- The antigens trigger an immune response: lymphocytes divide and produce antibodies specific to that antigen.
- Memory lymphocytes are also produced and remain in the blood.