Card Set Information

2013-12-13 08:08:37
home ec
home ec notes
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  1. Define Microbiology
    It is the study of micro-organisms-tiny living organisms that are not visible to the naked eye
  2. List some fungi
    Moulds, yeasts, large fungi
  3. List some bacteria
    Salmonella, e.coli
  4. List viruses
    Those that cause colds and flus
  5. What is a parasite?
    Feeds on living matter
  6. What is a saprophyte?
    Feeds on dead matter
  7. What is a psychrophille?
    A micro-organism that thrives at low temp -5 to 20
  8. Mesophiles?
    Thrive at 20-45c
  9. Thermophiles?
    Thrive at 45-75c
  10. Aerobic?
    Needs oxygen
  11. Pathogens?
    Disease causing bacteria
  12. Anaerobic?
    Don't require oxygen
  13. How do microbes feed on food?
    • Secrete enzymes onto their food source
    • Breaks food down into simple compounds
    • Simple compounds are  absorbed through cell wall
  14. Describe bacteria?
    • Microscopic unicellular organisms
    • Found everywhere
    • Pathogenic or non-pathogenic
  15. Structure of bacteria cell?
  16. Structure of bacteria cell simplified version
  17. Reproduction of bacteria
    • Assexually by binary fission
    • Produces genetically identical offspring
    • Short lifecycle-reproduce every 20 mins
    • New mutations spread very quickly
    • Rapid growth stops as bacteria compete for food,oxygen,moisture and space
    • Mature bacterial cell duplicates its nuclear material
    • Remaining cell divides forming 2 cells
  18. Diagram of bacteria reproduction
  19. Spore forming bacteria
    If conditions become unfavourable for bacterial growth, some bacteria form spores
    The spores that develop within a bacterial cell are called endospores
    Endopores grow tough wall around it
    Can stay dormant for years until conditions are ok for growth
    Bacilli and clostridia have the ability to form spores, which are highly resistant to heat,cold and disinfectants
  20. Diagram of spore formation
    pg 126
  21. Toxins
    Some bacteria produce waste called toxins
    Toxins can cause food poisoning, endo or exotoxins
    • Exotoxins:
    • Produced OUTSIDE bacterial cell
    • Before and after food is eat-responsible for toxic food poisoning
    • Clostridium botulinum
    • Botulinum cook at 121c for 4-6 mins kills of the bacteria
  22. Endotoxins 
    Produced in bacterial cells
    Released when the cells die
    Salmonella and listeria -responsible for toxic food poisoning
  23. Salmonella effects
    Fever, diarrhoea,vomming, cramps, onset 12-72 hours after eating food, lasts 3 to  days
  24. Classification of bacteria
    • Shape:
    • Spherical-cocci
    • Squiggly-sprilla
    • Rod-bacillus
    • Gram staining:
    • Positive 
    • Negative
  25. Characteristics of bacteria
    • Positive:
    • One cell thick
    • No flagella
    • Spore forming
    • Low resistance to antibiotics eg streptococci-throat

    • Negative:
    • Cell wall is 2 thin layers
    • Has flagellae
    • Non-spore forming
    • high resistance to antibiotics
    • Salmonella