Immune system

• What section of biology is being discussed?

  Recognition and immune system
• What enables the identification of pathogens?

  Specific molecules on cell surfaces
• What are the main molecules that identify pathogens?

  Antigens
• What is the definition of an antigen?

  Foreign proteins on cell surfaces
• How do pathogens survive in relation to antigens?

  They mutate their antigens
• What is antigenic variability?

  Mutations in antigens that change structure
• Why must flu vaccinations be updated annually?

  Due to antigenic variability of the virus
• What are the three kinds of immune responses?

  • Phagocytosis
  • Cell-mediated response
  • Humoral response
• What is phagocytosis?

  Engulfment of a pathogen by a phagocyte
• How does a phagocyte bind to a pathogen?

  Via receptors on its surface
• What forms when a pathogen is engulfed by a phagocyte?

  A phagosome
• What do lysosomes do in phagocytosis?

  Break down the pathogen into soluble materials
• What is an antigen presenting cell?

  A phagocyte that presents antigens
• What are the two types of lymphocytes?

  B cells and T cells
• Where do B cells mature?

  In the bone marrow
• Where do T cells mature?

  In the thymus gland
• What do T cells do when they bind to antigens?

  Stimulate rapid differentiation into clones
• What do cytotoxic T cells produce?

  Perforin
• What is the role of perforin?

  Makes holes in pathogen cell membranes
• What is the structure of an antibody?

  Y-shaped with four polypeptide chains
• What links the chains of an antibody?

  Disulfide bonds
• What is the constant region of an antibody?

  Region present in all antibodies
• What is the variable region of an antibody?

  Region that makes antibodies specific
• What is the process of the humoral response?

  1. Helper T cells stimulate B cells
  2. B cells undergo clonal selection
  3. Plasma cells produce antibodies
  4. Antibodies bind to antigens and destroy pathogens
• What is clonal selection?

  Rapid division of B cells by mitosis
• How do antibodies destroy pathogens?

  By agglutination of pathogens
• What is agglutination?

  Antibodies binding and clumping pathogens
• What is the primary response?

  First contact with a pathogen
• What is the secondary response?

  Second contact with a pathogen
• What do memory B cells do?

  Remember how to produce antibodies
• How does vaccination provide immunity?

  By forming memory B cells
• What is herd immunity?

  Immunizing the majority of the population
• What ethical issue is associated with vaccinations?

  Should vaccinations be compulsory?
• What is active immunity?

  Immunity from antibody production by the body
• What is passive immunity?

  Immunity from antibodies introduced from another source
• What are monoclonal antibodies?

  Antibodies isolated from a single B cell clone
• What is the main use of monoclonal antibodies?

  Drug targeting
• What is the ELISA test used for?

  Detection of antigens in diseases
• What is the first step in the ELISA test?

  Immobilizing the antigen of interest
• What happens after adding monoclonal antibodies in the ELISA test?

  They bind to their appropriate antigen