Bio Topic 3

• What is a pathogen?

  A micro-organism that causes diease
• What are examples of pathogens?

  Viruses - Reproduce via inserting genes into cells which causes them to produce more copies. E.g. measles & HIV

  Bacteria - Releases toxins into our body that damage cells. E.g. salmonella & gonorrhea

  Fungi - damages cells

  Protists: single - celled organisms e.g malaria is caused by a protist that infects red blood cells. Mosquitoes are the vector
• What are some examples of plant disease?

  Rose black spot (fungus) - Causes leaves to fall off

  Tobacco mosaic virus - discolours leaves, less chlorophyll leads to stunted growth
• What are examples of human defence mechanisms?

  Skin - acts as a barrier & produces sebum (an oil) to repel pathogens

  Nostril/bronchi - contains mucus which is a sticky substance that traps pathogens

  Stomach - contains hydrochloric acid that kills pathogens due to its low pH level

  Eyes - produce tears which are antiseptic and contain enzymes that kill bacteria
• What are examples of plant defence mechanisms?

  Physical - thorns, spikes and waxy cuticle

  Chemical - poisonous berries

  Mechanical - brittle leaves, leaf toughness and leaf rolling/folding
• What are types of white blood cells?

  Lymphocytes - produce antitoxins that neutralise toxins made by pathogen, and antibodies that bind to antigen of pathogen, only if they fit

  Phagocytes - ingests pathogens
• What happens if an unknown pathogen enters our body?

  Lymphocytes start making different shapes until the right one is found. Once the correct shape is found, T cells store it in our lymph nodes, ready for next time (immunity)
• What is a vaccine?

  A dead/inert version of a virus that's injected into our body, so we can gain immunity without becoming ill.
• What are antibiotics?

  Medications that kill bacteria but not viruses
• What are problems with synthetic drugs?

  Cost a lot of money to develop and side effects
• How are synthetic drugs assessed?

  They're put through trials to assess efficacy, toxicity and dose.

  They are tested on cell tissue, then animals and then humans
• What is a blind trial?


  When doctors give a test group a drug, and the control group is given a placebo without being made aware.
• What is a double blind trial?

  When both doctors and patients (groups) do not know which is which to eliminate bias.
• Why must a whole course of antibiotics be taken?

  To kill all bacteria, or more resistant bacteria will multiply and survive
• What 2 drugs were derived from nature?

  Aspirin - a painkiller, came from the bark of willow trees

  Penicillin - first antibiotic, came from a mould
• How are monoclonal antibodies made?

  Produced by clones of a cell that produces a desired antibody

  First, inject virus into a mouse. Lymphocytes in mouse produce complimentary antibodies. Then, lymphocytes combine with a tumour cell to form a hybridoma. The hybridoma produces monoclonal antibodies specific to virus. This is cloned to produce a lot of antibodies ready to treat patients
• What are the uses of monoclonal antibodies?

  • combat diseases
  • medical diagnosis
  • pathogen detection
  • identifying molecules:

  dye is bound to antibodies which attach to specific molecules
• What is the outcome of monoclonal antibodies?

  The side effects are much worse than expected