Antigens Flashcards
(9 cards)
What is an antigen?
A protein that stimulates an immune response leading to the product of an antibody.
How are cells identified by the immune system?
Each type of cell has specific molecules on its surface that identify it. These are often proteins with a specific tertiary structure.
What is an antibody?
A quaternary structure protein secreted by B lymphocytes in response to specific antigens. It binds specifically to antigens forming antigen-antibody complexes.
What types of cells and molecules can the immune system identify?
Pathogens - bacteria, fungi or viruses such as HIV.
Cells from other organisms of the same species - harmful for those with organ transplants.
Abnormal body cells - cancer cells.
Toxins - some pathogens release toxins into the blood such as cholera.
Explain the effect of antigen variability on disease and disease prevention
Antigens on pathogens change tertiary structure due to gene mutations. So the person is no longer immune from previous infection or vaccination. B memory cell receptors can’t bind to the new antigen on secondary exposure. The specific antibodies aren’t complementary to the changed antigen.
Explain how antibodies lead to the destruction of pathogens
Antibodies bind to antigens on pathogens forming an antigen-antibody complex. There is a specific tertiary structure so the binding site binds to complementary antigen.
Each antibody binds to 2 pathogens at a time causing agglutination (clumping) of pathogens.
Antibodies attract phagocytes.
Phagocytes bind to the antibodies and phagocytose many pathogens at once.
What are lymphocytes?
Cells that can identify non-self cells.
When are lymphocytes made?
When you are a fetus.
What causes an autoimmune disease?
When lymphocytes attack self cells.
