Pathogens

• What is health defined as?

  A state of mental, physical and social wellbeing, NOT just the absence of disease
• What is disease defined as?

  A departure from good health caused by a malfunction of the mind or body
• What are communicable diseases and how are they transmitted?

  • Caused by pathogens
  • Passed from one organism to another
  • Vectors carry pathogens (common vectors include water and insects)
• How are bacteria classified?

  By shape
• What is the difference between gram positive and gram negative bacteria?

  They have different cell walls that respond differently to antibiotics
• What type of organism are bacteria classified as?

  Prokaryotic
• What can bacteria release that makes us feel ill?

  Toxins
• What is the role of antibiotics in relation to bacteria?

  Antibiotics kill bacteria
• Name two diseases caused by bacteria.

  Cholera and TB
• What does a virus contain?

  DNA or RNA, never both
• Why are viruses not considered living organisms?

  They need a living host to survive
• How do viruses replicate?

  By making host cells copy their genetic material
• What are bacteriophages?

  Viruses that infect bacteria
• Can antibiotics kill viruses?

  No, antibiotics cannot kill viruses
• What type of organism are fungi classified as?

  Eukaryotic
• Name two diseases caused by viruses.

  Flu and HIV
• What are hyphae?

  Microscopic tubes that make up fungi
• How do fungi obtain nutrients?

  By excreting enzymes that digest substrates
• What is the difference between saprotrophic and parasitic fungi?

  Saprotrophic fungi live on dead material, while parasitic fungi live on a living host
• Name two diseases caused by fungi.

  Athletes foot and thrush
• What type of cells are protoctista?

  Unicellular Eukaryotic cells
• How do protoctista move?

  Often have flagella or cilia
• What do pathogenic protoctista often need to spread?

  Vectors to spread and infect their host
• Name two diseases caused by protoctista.

  Malaria and Giardiasis
• How do pathogens cause damage to the host?

  • Direct damage: viruses take over cell metabolism
  • Some protoctista digest host cells
  • Fungi use enzymes to digest host cells
  • Producing toxins: bacteria and some fungi produce toxins that interfere with cell biochemistry
  • The effect of the pathogen and the host's immune response causes disease symptoms