Infection + Response

• How are monoclonal antibodies produced?


  Antigen is injected into the mouse

  Extract lymphocytes that make the specific antibody to the antigen

  Lymphocytes are combined with tumour cell to form a hybridoma

  Hybridoma is cloned to create many cells that produce the antibody
• How does a vaccine work?


  Dead or inactive form of pathogen is injected

  White blood cells produce antibodies

  If injected specific antibodies are produced quickly

  Antibodies destroy the active pathogen
• pathogens

  microorganisms that cause disease
• bacteria

  a form of pathogen

  produce toxins that damage tissues and cause us to feel ill
• viruses

  a form of pathogen

  live and reproduce inside cells

  cause cell damage
• measles

  viral disease

  symptoms of fever and red skin rash

  can be fatal if complications

  most young children are vaccinated

  spread by inhalation of droplets from sneezes and coughs
• HIV

  initially causes a flu like illness

  virus that attacks the immune cells

  can develop to AIDS if the immune system becomes too badly damaged

  spread by sexual contact or exchange of bodily fluids
• Tobacco Mosaic Virus (TMV)

  widespread plant pathogen

  causes discolouration of the leaves

  lack of photosynthesis prevents growth of the plant
• salmonella

  • bacterial disease
  • spread by bacteria ingested food or unhygienic preparation conditions
  • poultry are vaccinated
  • causes fever, abdominal cramps, vomiting, diarrhoea
• Gonorrhoea

  • STD
  • symptoms of thick yellow/green discharge and pain when urinating
  • treated by penecillin
  • spread by sexual contact
  • controlled by antibiotics or barrier method of contraception
• Rose Black Spot

  • fungal disease
  • purple/black spots appear on leaves causing them to turn yellow and drop early
  • photosynthesis is reduced so less growth
  • spread by water/wind
  • treated by fungicides/removing affected leaves
• Malaria

  • pathogens causing it are protists
  • mosquito is a vector
  • causes recurrent episodes of fever/can be fatal
  • controlled by preventing breeding of mosquitos/using mosquito nets
• white blood cells help defend against pathogens by:

  • phagocytosis
  • antibody production
  • antitoxin production
• non specific defence systems of the body

  • skin
  • trachea and bronchi
  • nose
  • stomach
• Antibiotics

  • medicines that help cure bacterial disease by killing infective bacteria inside the body
  • specific bacteria should be treated by specific antibiotics
• Painkillers

  used to treat the symptoms of disease by do not kill pathogens
• It is difficult to develop drugs to kill viruses without also dmaging the body's tissues because the viruses live inside the cell
• Digitalis (the heart drug) originates from the foxglove
• Aspirin comes from a willow tree
• Penicillin was discovered by Alexander Fleming
• New drugs are tested for:

  • toxicity
  • efficacy
  • dose
• Preclinical Testing

  • first stage of testing
  • done in labs
  • uses cells, tissues and live animals
• Clinical Trials

  • use healthy volunteers and patients
  • low doses are given at the start
  • if the drug is safe further trials are carried out to find the optimum dosage
  • in double blind trials some patients are given a placebo
• Placebo

  a substance that is similar to the drug being tested but has no effect on the patients condition
• Placebo Effect


  when a patient expects the treatment to work and so feels better even though the treatment is having no effect
• Monoclonal Antibodies are produced from a single clone of cells and are specific to one binding site on one protein antigen
• A large amount of the monoclonal antibody can be collected and purified
• Uses of monoclonal antibodies:

  • pregnancy tests
  • in labs to measure the levels of hormones
  • to detect pathogens
  • to treat some diseases e.g cancer
  • to locate specific molecules in a cell or tissue
• Plant diseases can be identified by:

  • stunted growth
  • spots on leaves
  • areas of decay
  • malformed stems/leaves
  • discolouration
  • presence of pests
• Identification of plant diseases can be made by:

  • reference to a gardening manual/website
  • identifying the pathogen in a lab
  • using a testing kit containing monoclonal antibodies
• Ion deficiency conditions in plants:

  • stunted growth caused by nitrate deficiency
  • chlorosis causes by magnesium deficiency
• magnesium ions are needed to make chlorophyll
• nitrate ions are needed for proteinsynthesis and therefore growth
• Physical plant defence responses:

  • cellulose cell walls
  • tough waxy cuticle on leaves
  • bark on trees which falls off
• Chemical plant defence responses:

  • antibacterial chemicals
  • poisons to deter herbivores
• Mechanical adaptations of plants:

  • thorns and hairs to deter animals
  • leaves which droop and curl when touched
  • mimicry to trick animals
• why might a fluorescent dye be added to the monoclonal antibodies?

  in order to locate/identify a specific molecule
• why aren't monoclonal antibodies used as much as scientists hoped?

  because they create more side effects than expected