Biology: Infection and Response: Key terms

• Pathogen


  a disease-causing microorganism
• Vector


  an organism that carries a pathogen but does not suffer from the disease
• Toxin


  a poisonous chemical, produced by certain pathogens
• Non-specific defences


  the first line of defence against pathogens in general; includes skin, hair, mucus, etc.
• Immune system

  the body's defence system against infections and diseases (consists of white blood cells and antibodies)
• Phagocytosis


  the process by which one cell, such as a white blood cell, surrounds and engulfs another cell
• Antibody


  a protein produced in the body by the immune system to kill specific pathogens
• Antigen

  a marker molecule found on the surface of microorganisms
• Antitoxin


  a chemical released from white blood cells that can neutralise harmful toxins
• Immunity

  the ability to attack a pathogen before it causes disease due to a previous encounter with the pathogen
• Vaccination


  a liquid preparation containing inactive or dead pathogens, used to make the body produce antibodies to provide protection against disease
• Antibiotics


  medication used to kill bacterial pathogens inside the body
• MRSA


  (Methicillin-Resistant Staphylococcus Aureus) - an antibiotic-resistant bacterium; a 'superbug
• Digitalis


  a drug extracted from foxgloves, used to treat heart problems
• Aspirin


  a painkilling drug first extracted from the bark of willow trees
• Penicillin


  an antibiotic extracted from the Penicillium fungus
• Double-blind trial


  a trial where neither the patient nor the doctor know if the patient is receiving the test drug or a placebo
• Placebo


  a dummy drug given to patients during drug trials
• Monoclonal antibody


  an antibody produced by a single clone of cells
• Hybridoma


  a cell produced by the joining of a tumour cell and a white blood cell
• HCG


  a hormone found in urine during early pregnancy
• Tobacco-mosaic virus(TMV)


  a virus that attacks tobacco and related plants, causing discoloured patches on the leaves
• Aphid

  a small insect, often called 'greenfly', that sucks food out of the phloem of plants
• Deficiency disease


  a disease caused by the lack of an essential element in the diet
• Chlorosis


  a condition that means leaves produce insufficient chlorophyll
• Mimicry

  when one organism evolves to look or behave like an organism of another species as a defence mechanism