Biology

• Salmonella


  Bacterium spread through contaminated food, cured by thoroughly cooking food and antibiotics
• Tuberculosis


  Bacterium spread through air, cured by BCG vaccination or antibiotics
• Chlamydia


  Bacteria spread through sexual contact, reduced by condoms or antibiotics
• Athlete's foot


  Fungus spread through contact, cured by avoiding direct contact in likely present areas
• Potato Blight


  Fungus spread through air spores in warm, humid conditions, cured by crop rotation and fungicide spraying
• Aseptic Techniques

  1. Ensure microorganisms being investigated do not escape or become contaminated

  2. Prevent growth of unwanted, pathogenic microorganisms
• Examples of Aseptic Techniques

  • No eating or drinking in the lab
  • Using sterile loops when transferring cultures
  • Flaming culture bottle necks to prevent contamination
  • Sterilising or disposing of all used equipment
  • Washing hands thoroughly
• Pathogen

  Something that can make you sick
• How the nose defends against sickness

  • Hair
  • Mucuous Membranes
• How the skin defends against sickness

  • pH
  • Oils
  • Barrier - if barrier breaks then blood clots and scabs
• Antigens

  Chemicals on the surface of invading pathogens that cause special white blood cells called lymphocytes to react
• How lymphocytes react to antigens

  1. Produce Chemicals called Antibodies

  2. Stimulate Phagocytes to react

  3. Stimulate the production of Memory Lymphocytes which remember how to fight antigen
• Phagocytes


  They engulf and digest pathogens by enzymes
• Role of antibodies


  • They have a specific, complementary shape to an antigen
  • These shapes cause them to clump together on microorganisms' surface
  • Once clumped together they are immobilised=less likely to spread and more easily destroyed by phagocytes
• Response to first infections

  1. 1 Type of bacteria enters the body

  2. These bacteria have antigens on their surface that trigger the body's immune response

  3. White Blood Cells have Lymphocytes that produce Antibodies

  4. These antibodies attach to the foreign proteins on the bacteria's surface

  5. This causes clumping which stops bacteria from moving and reproducing

  6. Phagocytes engulf and digest bacteria
• Primary response


  The body's initial response to combat the first infection, during which it also makes memory lymphocytes
• Secondary response


  After the primary response, if the same microorganism is encountered again, memory lymphocytes produce high numbers of the correct antibody very quickly to prevent the person getting sick again
• How to become immune

  1. High enough levels of antibodies

  2. Capacity to produce high enough
• Active Immunity


  When the body is activated and produces the antibodies needed to fight an infection, either naturally or through vaccines
• Characteristics of Active Immunity

  • Slow acting
  • Provides long-lasting protection
• Passive Immunity


  When ready-made antibodies from another source are introduced to the body, e.g. breastfeeding or anti-venom
• Characteristics of Passive Immunity

  • Fast acting
  • Only lasts a short period of time
• Plant defense mechanism categories

  • Structural e.g. waxy cuticle
  • Chemical e.g. thick cell walls
• Antibiotics


  Chemicals produced by fungi that kill or prevent the growth of bacteria
• Alexander Fleming noticed a fungus contaminating a bacterial culture, concluding an antibacterial substance was diffusing from the fungus


  1920s
• Florey and Chain were able to isolate and begin large-scale production of penicillin


  1940s
• How Penicillin is commercially made

  1. The fungi that make penicillin are grown in large biodigesters or fermenters

  2. The penicillin is then extracted, purified and packaged in a process known as downstreaming
• Preclinical trials


  Involve testing a drug in a lab on cells and tissues, then on animals, and using computer modeling
• Purpose of preclinical trials

  • Check if the drug is poisonous or harmful
  • Check how effective the drug is
• Clinical Trials


  Initially use small groups of healthy, human volunteers, then larger groups, including patients who can potentially benefit
• Purpose of Clinical Trials

  • Determine the correct dosage required for the drug to be licensed for use
• Peer review


  New research and discoveries are scrutinized by other experts in the same field before being published
• Antibiotic resistance


  Antibiotics kill non-reliant bacteria, allowing resistant bacteria to survive and reproduce, increasing the resistant population
• Superbugs


  Also known as MRSA, bacteria that have become resistant to many antibiotics
• Why superbugs are a big problem in hospitals

  • Patients have weak immune systems
  • Patients may have open wounds allowing microorganism entry
  • The environment is antibiotic-rich, promoting resistance
• Measures hospitals take to prevent superbugs

  • Increased hygiene, i.e. wear gloves, clean up bodily fluids immediately
  • Greater care when administering antibiotics
  • Isolate 'superbug' patients from other patients