Microbiology Chapter 9 Review
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Questions and Answers

Which type of bacterial growth occurs after the lag phase in a growth curve?

  • Death phase
  • Lag phase
  • Log phase (correct)
  • Stationary phase

What is the primary purpose of quorum sensing in biofilm formation?

  • To resist environmental stresses
  • To produce energy more efficiently
  • To coordinate behavior among bacterial cells (correct)
  • To enhance nutrient absorption

Which statement best describes the difference between sterilization and disinfection?

  • Sterilization can be achieved through chemical means only, while disinfection can be physical or chemical.
  • Disinfection works only on inanimate objects, while sterilization applies to living tissues.
  • Disinfection kills all microbes, while sterilization only reduces their numbers.
  • Sterilization eliminates all forms of microbial life, whereas disinfection reduces harmful microbes. (correct)

How do facultative anaerobes differ from obligate aerobes in terms of oxygen requirements?

<p>Facultative anaerobes can utilize oxygen but do not require it, while obligate aerobes need oxygen to survive. (C)</p> Signup and view all the answers

What is the purpose of using a chemostat in microbial growth studies?

<p>To maintain a consistent growth environment (A)</p> Signup and view all the answers

What is one limitation of using the viable cell count method like CFU counting?

<p>It cannot distinguish between live and dead cells. (C)</p> Signup and view all the answers

What role does the DRT (Decimal Reduction Time) play in assessing microbial control methods?

<p>It determines the time required to kill 90% of the microorganisms. (A)</p> Signup and view all the answers

Which of the following methods is classified as an ionizing radiation technique for microbial control?

<p>Gamma rays (A)</p> Signup and view all the answers

What defines a broad-spectrum antibiotic compared to a narrow-spectrum antibiotic?

<p>Broad-spectrum antibiotics target a wider variety of bacteria, while narrow-spectrum antibiotics target specific types. (C)</p> Signup and view all the answers

Which of the following is a physical method of microbial control?

<p>Heat sterilization (A)</p> Signup and view all the answers

Which of the following accurately describes the steps involved in biofilm formation?

<p>Adhesion, EPS production, maturation, and detachment (A)</p> Signup and view all the answers

What is the primary limitation of using the disk diffusion method for disinfectant testing?

<p>It cannot determine the minimum inhibitory concentration (MIC). (A)</p> Signup and view all the answers

Which of the following characteristics is typical of thermophiles?

<p>They favor growth at temperatures ranging from 45°C to 80°C. (B)</p> Signup and view all the answers

What is the main distinction between antisepsis and degerming?

<p>Antisepsis is the reduction of microbial load on living tissue; degerming refers to the physical removal of microbes. (D)</p> Signup and view all the answers

Which method is common for testing the effectiveness of chemical preservatives?

<p>Use-dilution test (A)</p> Signup and view all the answers

In which scenario would an obligate anaerobe be most likely to thrive?

<p>In a gut devoid of oxygen. (B)</p> Signup and view all the answers

What distinguishes halotolerant organisms from halophiles?

<p>Halophiles require high salt concentrations for growth, while halotolerant can grow in varying conditions. (B)</p> Signup and view all the answers

Which of the following statements accurately reflects the role of EPS in biofilms?

<p>EPS provides structural integrity and protection to the bacterial community. (C)</p> Signup and view all the answers

Which process utilizes both physical and chemical agents to reduce microbial populations on critical items?

<p>Sterilization (C)</p> Signup and view all the answers

What is the significance of selective toxicity in antimicrobial drugs?

<p>It ensures the drug is effective without harming the host cells. (B)</p> Signup and view all the answers

Which method is used to measure microbial growth utilizing a cell counter?

<p>Coulter counter (B)</p> Signup and view all the answers

What type of microorganism is characterized by its ability to grow optimally at a pH below 5.5?

<p>Acidophiles (A)</p> Signup and view all the answers

Which of the following is a chemical method of microbial control that alters DNA structure?

<p>Alkylating agents (C)</p> Signup and view all the answers

In a microbial growth curve, which phase is characterized by the highest rate of cell division?

<p>Log phase (C)</p> Signup and view all the answers

Which of the following organisms can survive in high salinity environments?

<p>Halophiles (D)</p> Signup and view all the answers

What is the primary advantage of using a chemostat in bacterial culture?

<p>Reproducible and controlled growth conditions (D)</p> Signup and view all the answers

Which of the following methods is classified as a physical control method against microbial growth?

<p>Radiation (C)</p> Signup and view all the answers

What defines the concept of selective toxicity in antimicrobial drugs?

<p>Targeting specific structures or functions in pathogens without harming the host (A)</p> Signup and view all the answers

What test determines the effectiveness of disinfectants based on the number of microorganisms killed?

<p>Use-dilution test (C)</p> Signup and view all the answers

Which of the following statements about biofilms is true?

<p>EPS is a crucial component for biofilm structural integrity. (A)</p> Signup and view all the answers

Flashcards

Binary Fission

A type of asexual reproduction in bacteria where a single cell divides into two identical cells.

Generation Time

The time it takes for a bacterial population to double.

Growth Curve

A graph that shows the different phases of bacterial growth (Lag, Log, Stationary, Death).

Sterilization

The complete removal or destruction of all microbial life, including bacterial spores.

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Antimicrobial drugs

Substances that kill or inhibit the growth of microorganisms.

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Selective toxicity

A characteristic of antimicrobial drugs where they harm the infectious microbes, but not the host cells.

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Microbial death curve

A graph showing the rate at which microorganisms die under specific treatment conditions.

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Chemostat

A device that maintains a continuous culture of microorganisms at a desired growth rate.

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Biofilms

Complex microbial communities that adhere to surfaces and produce extracellular polymeric substances (EPS).

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Disinfection

A process of reducing microbial load, often on inanimate objects.

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Z ring assembly

A ring-like structure made of protein FtsZ that forms in the middle of a dividing bacterial cell, guiding cell wall synthesis and ultimately dividing the cell into two daughter cells.

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Lag phase

The initial phase of bacterial growth where cells adapt to their new environment and prepare for rapid growth, but don't immediately increase in number.

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Log phase

The phase of exponential growth where bacteria divide at their fastest rate, doubling their population in a set time period.

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Stationary phase

The phase where the bacterial population growth slows down and eventually plateaus as resources become limited and waste products accumulate.

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Death phase

The phase where bacterial population declines as more cells die due to unfavorable conditions like lack of nutrients and increasing waste.

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Sustainable growth

The ability of a population to maintain a constant growth rate over time due to constant nutrient supply and removal of waste products.

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Microscopic counting

Directly counting microbial cells under a microscope, using a counting chamber with known volume.

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Viable counting

Measuring the number of living cells in a sample by culturing them on a growth medium and counting the colonies that form.

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Biofilm formation

A process where bacteria attach to a surface, form a community, and produce a protective extracellular matrix called EPS.

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What is the Z ring?

A ring-like structure made of protein FtsZ that forms in the middle of a dividing bacterial cell. It guides the synthesis of a new cell wall, ultimately dividing the cell into two daughter cells.

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Growth Curve Phases

The four phases of bacterial growth: Lag, Log, Stationary, and Death. Bacteria go through these phases as they adapt to their environment, grow rapidly, reach a plateau, and eventually die.

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Quorum Sensing

A system in bacteria where they communicate with each other using chemical signals to coordinate their behavior, like biofilm formation and antibiotic resistance.

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Antisepsis

The process of killing or inhibiting the growth of microbes on living tissue.

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Study Notes

Chapter 9 Review

  • Binary Fission: Steps and Z ring assembly are key aspects
  • Generation Time: Calculating population time (generally, a calculator isn't needed) is important
  • Growth Curve: Lag, Log, Stationary, and Death phases are significant; understanding sustainable growth and chemostats is essential. Learn proper measurement techniques (microscopic, fluorescent, Coulter, viable, O.D., membrane filtration, MPN).
  • Growth Measurement: Methods include CFU counting (pour plate vs. spread plate), and count ranges for viable counts
  • Alternate Growth Patterns: Different growth patterns (biofilms with EPS formation, quorum sensing) exist and affect human health.
  • Media for Bacterial Growth: Selective and differential media will be essential to understand along with other types of media.
  • Environmental Factors: Factors influencing generation time include oxygen (types of aerobes and anaerobes), FTM, aerotolerance, pH (neutrophiles, acidophiles), temperature (mesophiles, psychrophiles, thermophiles), osmotic pressure (halophiles, halotolerance), barometric pressure, and light.

Chapter 13 Review

  • Sterilization vs. Disinfection vs. Antisepsis vs. Degerming vs. Sanitation: Distinguish the meanings and methods.
  • BSL Levels (1-4): Understand requirements and examples for each level
  • Clean in Clinic: Critical, semicritical, and noncritical items are categorized by how they're cleaned
  • -Cidal vs. -Static: Understand the difference in action
  • Microbial Death Curve and DRT: Understand the concepts.
  • Physical Means of Control: Heat (dry vs. moist, autoclave, pasteurization), refrigeration/freezing, pressure (lyophilization, water activity), radiation (ionizing vs. nonionizing), filtration (membrane, HEPA), and sonication are methods to control microbial growth, and their limitations and how they work.
  • Chemical Means of Control: Phenolics, heavy metals, halogens, alcohols, surfactants, bisbiguanides, alkylating agents, peroxygens, and supercritical fluids are types of chemical agents used to control microbial growth. Know how they work, limitations, examples and specific uses.
  • Disinfectant/Preservative Testing: Phenol coefficient, disk diffusion, use-dilution, and in-use tests are used to evaluate these agents.

Chapter 14 Review

  • Brief History of Antimicrobials: Key figures like Ehrlich, Klarer, Mietzch, Domagk, Fleming, Hodgkin, and Waksman were important in developing antimicrobials
  • Narrow vs. Broad Spectrum: Understand the difference between narrow-spectrum and broad-spectrum antimicrobials, and their usefulness.
  • Dosing and Interactions: How drug dosages impact results and any interactions between drugs.
  • Selective Toxicity: Focus on the ability of drugs to target bacteria without harming the host.
  • Studying Antimicrobial Drugs: Classify drugs by drug class, understand Mechanism of Action (MOA), target pathogens, common uses, challenges, and adverse side effects. Know all antimicrobials, pathways, and actions from the slides.
  • Antibiotic Resistance: Understand its acquisition mechanisms, special resistance, and MDRs. Know organisms such as ESKAPE pathogens (VRE, VRSA, VISA, MRSA, ESBLs, CRE, MDR-TB, XDR-TB) Understand resistance testing.
  • Testing for Efficacy: Kirby-Bauer, dilution tests (MIC, MBC, Etest), are essential methods for evaluating antimicrobials.

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Description

This quiz covers essential concepts from Microbiology Chapter 9, focusing on bacterial growth processes such as binary fission, generation time, and the growth curve phases. It also explores nutrient media, environmental factors, and alternate growth patterns that impact human health. Understanding these key elements is crucial for comprehending microbial behavior and laboratory practices.

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