Infection and Response

• Types of communicable diseases

  • Rose black spot
  • Fungal diseases
  • Bacterial diseases
  • Viral diseases
  • Protist diseases
• Pathogens

  Microorganisms that cause disease
• Pathogens

  Reproduce rapidly and cause symptoms by damaging cells or secreting toxins
• Viruses

  Enter and reproduce inside cells, causing cell death
• Transmission prevention

  1. Improving hygiene

  2. Using contraception

  3. Vaccination

  4. Destruction of infected plants/animals
• Herd immunity


  Protects those unable to receive vaccinations
• Vaccination

  1. Contains dead/attenuated version of pathogen

  2. Triggers an immune response

  3. Memory cells remain - if pathogen re-enters body, it is recognised and destroyed quickly
• Painkillers


  Only treat symptoms
• Antibiotics


  Kill bacteria only
• Resistance


  Due to overuse
• Non-specific defences against disease

  • Skin
  • Nose
  • Trachea/bronchi
  • Stomach
• Immune response

  White blood cells produce antibodies, antitoxins, and engulf pathogens in phagocytosis
• Drugs


  Originally made from plants and microorganisms, now synthesised
• New drugs

  1. Must undergo extensive testing

  2. Preclinical testing and clinical trials test for toxicity, efficacy, and dose
• Vaccination programmes

  Reduce the spread of disease
• Ways of spread of communicable diseases

  • Direct contact
  • Airborne microorganisms
  • Indirect contact (e.g. through infected surfaces)
  • Contaminated food and drink
• Source: AQA
• Links: https://bit.ly/pmt-cc, https://bit.ly/pmt-cc, https://bit.ly/pmt-edu
• Production

  • Function
  • Diagnosis
  • Treatment
  • Applications
• Mouse lymphocytes


  Stimulated to produce a particular antibody
• Formation of hybridoma cells

  Lymphocytes are extracted and fused with cancer cells
• Hybridoma cells


  Selected hybridoma cells are cloned to produce many identical copies
• Large quantities of antibodies can be produced
• Antibodies

  • Purified
  • Highly specific to one antigen
  • Target specific cells or chemicals in the body
• Pregnancy tests


  • Measure the concentration of chemicals in the blood
• Pregnancy tests


  • Locate substances in cells or tissues using a fluorescent dye
• Cancer treatment

  • Targets cancer cells only
• Monoclonal antibody

  • Bound to radioactive substance
  • Bound to toxin
  • Bound to drugs
• Detect pathogens

  • Targets HCG hormone
  • e.g. HIV, AIDS
• Expensive to produce
• Unwanted side effects