3.2.4 Cell recognition and the immune system

• Active Immunity


  Resistance to disease resulting from the activities of an individual’s own immune system whereby an antigen induces plasma cells to produce antibodies.
• AIDS 


  The disease caused by HIV.
• Allergen 


  A normally harmless substance that causes the immune system to produce an immune response.
• Allergy


  The response of the immune system to an allergen.

  e.g. hay fever
• Antibiotic 


  A substance produced by a living organism that can destroy or inhibit the growth of microorganisms.
• Antibiotic resistance

  The development in microorganisms of mechanisms that prevent antibiotics from killing them.
• Antibody

  A protein produced by lymphocytes in response to the presence of the appropriate antigen.
• Antigen

  A molecule that triggers an immune response by lymphocytes.
• Antigen-presentation 


  When and antigen-presenting cell e.g. phagocyte displays foreign antigens on their own cell-surface membrane.
• Antigenic variability

  Pathogen may mutate frequently so that its antigens change suddenly rather than gradually which means vaccines become ineffective because the new antigens on the pathogen are no longer recognized by the immune system.
• Artificial immunity

  A type of active immunity resulting from vaccination. It involves inducing an immune response in an individual without them suffering symptoms of the disease.
• Attachment protein

  The capsid can have these which are essential to allow the virus to identify and attach to a host cell.
• B Cell (B Lymphocyte)

  A type of white blood cell that is produced and matures within the bone marrow. They produce antibodies as part of their role in immunity.
• Cancer

  A disease, resulting from mutations, that leads to uncontrollable cell division and the eventual formation of a group of abnormal cells called a tumour.
• Capsid

  A protein coat which encloses the nucleic acid in a virus.
• Carcinogen

  A chemical, form of radiation or other agent that causes cancer.
• Carrier molecule (carrier protein)

  A protein on the surface of a cell that helps to transport molecules and ions across plasma membrane.
• Cell-mediated immunity

  The type of response when T lymphocytes respond to antigens that are presented on a body cell.
• Clonal Selection

  As the receptor on a helper T cell attaches to the antigen this activates the T cell to divide rapidly by mitosis and form a clone of genetically identical cells. These cloned T cells stimulate B cells to divide and form a clone of identical B cells all of which produce the antibody that is specific to the foreign antigen.
• ELISA test

  Enzyme linked immunosorbent assay which uses antibodies to detect the presence and quantity of a protein in a sample.
• Enzyme

  A protein or RNA that acts as a catalyst and so alters the speed of a biochemical reaction.
• Epidemiology

  The study of the spread of disease and the factors that affect this spread.
• Foreign (non-self)

  Not your own body's cells and molecules.
• Glycoprotein

  Substance made up of a carbohydrate molecule and a protein molecule.
• Herd Immunity

  Arises when a sufficiently large proportion of the population has been vaccinated which makes it difficult for a pathogen to spread within that population.
• HIV

  Human immunodeficiency virus which causes the disease acquired immune deficiency syndrome (AIDS). It has a lipid envelope, attachment proteins, a capsid and two single strands or RNA and enzymes.
• Humoral Immunity

  The type of response which involves B lymphocytes and antibodies.
• Immunity

  The means by which the body protects itself from infection.
• Lymph

  A slightly milky fluid found in lymph vessels and made up of tissue fluid, fats and lymphocytes.
• Lymphocytes

  Types of white blood cell responsible for the immune response, they become activated in the presence of antigens.
• Lysosome


  Contain enzymes called lysozymes which they release into the phagosome which hydrolyse the bacterium.
• Memory B Cells

  Some B develop into memory cells which can respond to future infections by the same pathogen by dividing rapidly and developing into plasma cells that produce antibodies as part of the secondary response.
• Monoclonal antibodies

  Antibodies produced by a single clone of cells.
• Mutagen

  Any agent that induces a mutation.
• Natural Immunity

  A type of active immunity resulting from an individual becoming infected with a disease under normal circumstances.
• Passive immunity

  Resistance to disease that is acquired from the introduction of antibodies from another individual, rather than an individual's own immune system.
• Pathogen

  Any microorganism that causes disease.
• Phagosome

  A vesicle formed as the bacterium is engulfed by the phagocyte. The lysosome release their lysozymes into the phagosome.
• Phagocyte

  Type of white blood cell which carries out a non-specific immune response and ingests and breaks down pathogens by phagocytosis.
• Phagocytosis

  Mechanism by which cells engulf particles to form a vesicle or a vacuole.