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Microbial Control and Norovirus
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Microbial Control and Norovirus

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@TroubleFreeVolcano6636

Questions and Answers

What occurs when bacteria are exposed to heat or disinfectants?

  • Bacteria die at a constant rate. (correct)
  • Survivors multiply instantly.
  • All cells die instantly.
  • Only a percentage of bacteria are affected.

    • In the logarithmic death rate, what does a linearized curve represent?

  • The relationship between time and percentage of survivors. (correct)
  • The varying responses of different microbial types.
  • The constant death rate of all microbes.
  • The direct impact of disinfectants over time.

    • What is a primary mechanism of action for microbial control agents?

  • Synthesis of new proteins.
  • Enhancing replication of nucleic acids.
  • Alteration of the cell wall or plasma membrane permeability. (correct)
  • Increasing metabolism of the cells.

    • Which of the following is NOT a mechanism by which microbial control agents act?

    <p>Increasing cell wall stability.</p> Signup and view all the answers

    How does the size of a microbial population affect the time taken to eliminate it?

    <p>Larger populations take longer to eliminate than smaller ones.</p> Signup and view all the answers

    What is often targeted during microbial control processes?

    <p>Enzyme folding structure.</p> Signup and view all the answers

    Which physical method is commonly used for microbial control?

    <p>Radiation exposure.</p> Signup and view all the answers

    What happens to nucleic acids when they are damaged by microbial control methods?

    <p>They cannot replicate or produce proteins.</p> Signup and view all the answers

    What is the primary reason alcohols are ineffective as antiseptics against wounds?

    <p>They create a coagulation layer of protein.</p> Signup and view all the answers

    Which of the following metals is known for preventing mildew in paint?

    <p>Mercuric chloride</p> Signup and view all the answers

    Which statement best describes the effectiveness of ethanol as an antiseptic?

    <p>It is more effective when diluted as it requires water to act.</p> Signup and view all the answers

    Isopropanol is considered the best antiseptic because:

    <p>It is more effective at denaturing proteins compared to other alcohols.</p> Signup and view all the answers

    What is the primary mechanism by which heavy metals exert antimicrobial activity?

    <p>They denature proteins by binding to sulfhydryl groups.</p> Signup and view all the answers

    What is the primary method of microbial control typically used to achieve sterilization?

    <p>Heat application</p> Signup and view all the answers

    Which of the following statements best describes bacteriostatic agents?

    <p>They inhibit the growth of bacteria without killing them.</p> Signup and view all the answers

    In the context of microbial control, what does sanitization refer to?

    <p>Lowering microbial counts on surfaces to safe levels.</p> Signup and view all the answers

    Which factor does NOT affect the rate of microbial death during treatment?

    <p>Color of the solution used</p> Signup and view all the answers

    Which term refers to the absence of significant contamination?

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

    What is the key difference between disinfection and antisepsis?

    <p>Disinfection is for surfaces; antisepsis is for living tissues.</p> Signup and view all the answers

    Which of the following methods specifically targets and kills endospores, such as those formed by Clostridium botulinum?

    <p>Commercial sterilization</p> Signup and view all the answers

    What role do antagonism and synergism play in microbial treatment?

    <p>They indicate the effectiveness of combined antimicrobial agents.</p> Signup and view all the answers

    What is the primary function of surfactants like soaps?

    <p>Emulsify fats and facilitate washing away</p> Signup and view all the answers

    Which statement accurately describes quaternary ammonium compounds (quats)?

    <p>They enhance membrane permeability leading to plasmolysis.</p> Signup and view all the answers

    What is the role of sulfur dioxide in food preservation?

    <p>It acts as a disinfectant to prevent spoilage.</p> Signup and view all the answers

    Organic acids, like sorbic acid, primarily function by:

    <p>Interfering with the metabolism of bacteria and fungi.</p> Signup and view all the answers

    Which of the following antibiotics is considered to be broad spectrum?

    <p>Tetracyclines, which can inhibit a wide range of bacteria.</p> Signup and view all the answers

    What characteristic of acid-anionic sanitizers limits their effectiveness?

    <p>Their effectiveness is reduced at higher pH levels.</p> Signup and view all the answers

    Which type of bacteria are more susceptible to quaternary ammonium compounds?

    <p>Gram-positive bacteria.</p> Signup and view all the answers

    What is a significant limitation of using antibiotics as food preservatives?

    <p>They may lead to antibiotic resistance in humans.</p> Signup and view all the answers

    What is the primary mechanism by which high pressure denatures proteins?

    <p>It changes the protein's tertiary structure.</p> Signup and view all the answers

    Which method of microbial control uses the absence of water to prevent metabolism?

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

    What type of radiation is effective at causing lethal mutations in DNA by ionizing water?

    <p>Ionizing radiation</p> Signup and view all the answers

    What phenomenon occurs when osmotic pressure is applied using salts and sugars?

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

    Which component is critical in assessing the effectiveness of chemical disinfectants?

    <p>Time of exposure</p> Signup and view all the answers

    Which type of radiation creates thymine dimers by disrupting DNA structure?

    <p>Non-ionizing radiation</p> Signup and view all the answers

    Which method of microbial control involves the removal of moisture and can preserve viability for years?

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

    What is a key characteristic of ionizing radiation compared to non-ionizing radiation?

    <p>It creates reactive hydroxyl radicals.</p> Signup and view all the answers

    Study Notes

    Norovirus

    • Known as the "winter vomiting bug," norovirus causes gastroenteritis, also referred to as "infectious diarrhea."
    • The virus primarily infects and replicates in the small intestine.

    Terminology of Microbial Control

    • Sepsis: Presence of bacterial contamination in the body.
    • Asepsis: Condition of being free from significant contamination; crucial in surgical techniques to prevent infection.
    • Sterilization: Complete removal or destruction of all microbial life, often achieved through heat.
    • Commercial Sterilization: Targeted method to eliminate Clostridium botulinum spores in canned goods, which can produce a potent neurotoxin.
    • Disinfection: Process of eliminating harmful microorganisms from inanimate objects.
    • Antisepsis: The destruction of harmful microorganisms on living tissue.
    • De-germing: Mechanical removal of microbes from a localized area.
    • Sanitization: Reduction of microbial counts on surfaces to safe levels.
    • Biocide (Germicide): Agents that kill microbes, while bactericidal specifically kills bacteria, and bacteriostatic inhibits bacterial growth.

    Rate of Microbial Death

    • Treatment effectiveness influenced by microbial count, environmental factors (like temperature and pH), exposure time, and microbial characteristics.
    • Bacterial death occurs at a consistent rate, often visualized through a logarithmic plot showing diminishing survivors post-treatment.
    • Larger populations take longer to fully eliminate than smaller populations when using an equal rate of killing.

    Microbial Control Agents: Mechanisms of Action

    • Cell Wall or Membrane Alteration: Disruption leads to cell leakage and death.
    • Protein Damage: Denaturation of proteins results in loss of function, particularly enzymes.
    • Nucleic Acid Damage: Inability to replicate or synthesize proteins due to chemical, heat, or radiation impact.
    • Protein Synthesis Interference: Affects ribosomes and polymerases, essential for DNA and RNA synthesis.

    Physical Methods of Microbial Control

    • High Pressure: Denatures proteins and disrupts cell function.
    • Desiccation: Absence of water halts metabolism and keeps cells dormant for extended periods.
    • Osmotic Pressure: Use of high salt or sugar concentrations causes plasmolysis in microbes.
    • Radiation: Effective methods include:
      • Ionizing Radiation: High-energy radiation causing DNA damage through radical formation.
      • Non-Ionizing Radiation: UV rays create thymine dimers, leading to mutations.

    Chemical Methods of Microbial Control

    • Concentration and pH: Key factors in disinfectant effectiveness; longer contact time generally improves efficacy.

    Disinfectant Types

    • Alcohols: Denature proteins and dissolve lipids but are ineffective against non-enveloped viruses and endospores.
    • Heavy Metals: Small amounts, like silver or mercury, can kill microbes by protein denaturation.
    • Surface-Active Agents (Surfactants): Lower surface tension to help remove or reduce microbes; soaps emulsify fats, while quaternary ammonium compounds are strong against gram-positive bacteria.
    • Chemical Food Preservatives:
      • Organic Acids: Safe, non-toxic options that inhibit microbial metabolism, such as sorbic and benzoic acids.
      • Nitrites/Nitrates: Prevent germination of endospores in preserved foods.

    Antibiotics

    • Produced by bacteria, antibiotics inhibit or kill other bacteria and are typically broad-spectrum.
    • Primarily used for treating infections rather than as food preservatives, tested for effectiveness through methods like the Kirby-Bauer test.

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    Related Documents

    6-Ch.7 Control of Microbial Growth Physical & Chemical.pdf

    Description

    This quiz covers key concepts related to norovirus and the terminology surrounding microbial control. You'll explore terms such as asepsis, sterilization, and disinfection, along with their significance in preventing infections. Test your understanding of these important topics in microbiology.

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