Microbiology Overview
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Questions and Answers

Which of the following categories do not belong to the main divisions of micro-organisms?

  • Protozoa
  • Fungi
  • Insects (correct)
  • Bacteria

    • What characteristic distinguishes eukaryotic cells from prokaryotic cells?

  • Always unicellular
  • Complex structure and membrane-bound organelles (correct)
  • Simple composition
  • Presence of a nucleoid

    • Which of the following is NOT typically needed for microbial growth?

  • Appropriate temperature
  • Hydration
  • Sufficient nutrients
  • High radiation levels (correct)

    • How are prokaryotic cells primarily characterized?

    <p>Having a nucleoid without a membrane</p> Signup and view all the answers

    What role do microorganisms play in the human body?

    <p>They can support health as part of normal microflora.</p> Signup and view all the answers

    Which type of organism is classified as always unicellular?

    <p>Bacteria</p> Signup and view all the answers

    What is the primary focus of microbiology?

    <p>The study of organisms too small to be seen clearly</p> Signup and view all the answers

    Which statement correctly describes a feature of eukaryotic organisms?

    <p>They often have a defined nucleus.</p> Signup and view all the answers

    What is the primary factor influencing the establishment of the microbiome?

    <p>Mode of delivery</p> Signup and view all the answers

    Which of the following is NOT a key feature of microbial enzymes?

    <p>They are consumed during reactions</p> Signup and view all the answers

    Which type of toxin is produced by bacteria and is characterized by high toxicity and the ability to elicit strong immune responses?

    <p>Exotoxin</p> Signup and view all the answers

    What role do metabolites play in dentistry, particularly related to Streptococcus mutans?

    <p>They lead to enamel dissolution</p> Signup and view all the answers

    What aspect of microorganisms is crucial for their disease-causing potential?

    <p>Defenses of the microorganisms</p> Signup and view all the answers

    Which feature distinguishes endotoxins from exotoxins?

    <p>Endotoxins are part of the bacterial cell structure</p> Signup and view all the answers

    How do microbial enzymes assist in bacterial invasiveness?

    <p>By degrading the host response</p> Signup and view all the answers

    In what way does the microbiome change over time?

    <p>It increases in complexity with age</p> Signup and view all the answers

    What is a key factor that affects microbial growth related to water availability?

    <p>Microbial growth can commence once water is added to dehydrated food.</p> Signup and view all the answers

    How does temperature affect bacterial growth according to the relevant graph?

    <p>There is an optimal temperature range for bacterial growth.</p> Signup and view all the answers

    Which statement accurately describes the effect of light on parasitic micro-organisms?

    <p>Dark conditions are ideal for the survival of parasitic micro-organisms.</p> Signup and view all the answers

    What basic nutrient requirements do microbes share with higher forms of life?

    <p>Energy, nitrogen, carbon, water, and sulfur sources.</p> Signup and view all the answers

    What role does nutrition play in microbial growth?

    <p>Specific nutrients can enhance microbial growth.</p> Signup and view all the answers

    Which of the following statements about respiration in bacteria is correct?

    <p>Respiration affects the metabolic processes of bacteria.</p> Signup and view all the answers

    What is the effect of drying on different microbial species?

    <p>Staphylococci can survive in dry environments for extended periods.</p> Signup and view all the answers

    What is one effect of UV light on microorganisms?

    <p>UV light is lethal to most parasitic organisms.</p> Signup and view all the answers

    Study Notes

    Microbiology

    • Study of organisms too small to be seen with the naked eye; 0.1-0.2mm diameter
    • Known as micro-organisms or microbes
    • Includes: bacteria, viruses, fungi, algae, and protozoa

    Eukaryotes

    • Large and complex
    • Have a clearly defined nucleus
    • Membrane bound organelles
    • Single or multi-cellular

    Prokaryotes

    • Small and simple
    • Have a nucleoid with no membrane
    • Lacks internal membrane structure
    • Always unicellular

    Micro-organisms in Health

    • Microbes support us in health

    Establishment of Human Microbiome

    • Microbial introduction and establishment of microbiome is a random process
    • Influenced by factors including: mode of delivery, diet, age, geographical location, and lifestyle

    Micro-organisms and Disease

    • The disease potential of microbes is related to their products, antigenic nature, defences, and the host
    • Disease potential is influenced by:
      • Products: endotoxins, exotoxins, metabolites, enzymes
      • Antigenic nature: ability to trigger immune response
      • Defences: mechanisms for survival within the host
      • The host: individual susceptibility and immune response

    Microbial Enzymes

    • Enzymes are catalysts bacteria use to break down materials or synthesize energy and building requirements
    • Enzymes can produce changes in other substances without undergoing change themselves
    • Microbial enzymes support invasiveness by:
      • Allowing easy spread
      • Providing protection
      • Degrading host response

    Environmental Microbial Growth Considerations

    • Factors influencing microbial growth: temperature, pH, water, light, nutrition, and respiration

    Temperature

    • Most microbes grow best at specific temperature ranges:
      • Psychrophiles: cold-loving microbes
      • Mesophiles: moderate-temperature loving microbes
      • Thermophiles: heat-loving microbes
      • Hyperthermophiles: extreme heat-loving microbes

    Moisture

    • 80% of a microbial cell is water
    • Drying is tolerated differently by different species
    • Bacteria may not grow in dehydrated food, but growth may recommence once water is added

    Light

    • Parasitic micro-organisms grow and survive best in darkness
    • UV light is lethal and used in some types of sterilization
    • X-rays damage microbe DNA and can be used to sterilise medical supplies

    Nutrition

    • Basic requirements similar to higher forms of life: energy, nitrogen, carbon, water, and sulphur
    • Different enzyme systems specific in breakdown of certain nutrient compounds
    • Microbial growth can be enhanced by enriching the growth medium with specific nutrients and can be retarded using growth inhibitors

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