Microbiology Chapter 9 & 13 Review
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Questions and Answers

What is a characteristic feature of the growth curve during the Lag phase?

  • Rapid cell division occurs.
  • Nutrient depletion begins.
  • Cells are adapting to their environment. (correct)
  • The population declines rapidly.

Which method is used to measure viable bacterial counts?

  • Optical density measurement
  • Membrane filtration (correct)
  • Fluorescent counting
  • Microscopic counting

What is an example of a selective media?

  • Blood agar
  • MacConkey agar
  • Mannitol salt agar (correct)
  • Nutrient broth

Which of the following represents an obligate anaerobe's growth condition?

<p>Does not require oxygen and may be harmed by it (C)</p> Signup and view all the answers

What distinguishes disinfectants from antiseptics?

<p>Disinfectants can kill all microbial forms. (A)</p> Signup and view all the answers

What is the primary purpose of using a chemostat?

<p>To maintain continuous microbial growth (C)</p> Signup and view all the answers

Which of the following methods is not a physical means of microbial control?

<p>Halogen treatment (B)</p> Signup and view all the answers

What contribution did Alexander Fleming make to antimicrobial history?

<p>Discovery of the antibiotic penicillin (A)</p> Signup and view all the answers

Which of the following antimicrobial drug characteristics is described as 'narrow spectrum'?

<p>Effective only against specific types of bacteria (C)</p> Signup and view all the answers

What does the DRT (Decimal Reduction Time) measure?

<p>Time required to kill 90% of microorganisms (C)</p> Signup and view all the answers

What is a common characteristic of psychrophiles in relation to temperature?

<p>They can grow at temperatures below 15°C. (B)</p> Signup and view all the answers

Which term defines the process by which microbial growth is decreased or inhibited without killing the organism?

<p>-static (B)</p> Signup and view all the answers

What is the primary function of quorum sensing in biofilms?

<p>To regulate gene expression in response to cell density. (B)</p> Signup and view all the answers

Which of the following best describes a difference between sterilization and disinfection?

<p>Sterilization eliminates all microorganisms, while disinfection reduces them. (A)</p> Signup and view all the answers

What is the role of the Z ring during binary fission?

<p>It helps in the formation of the cell wall during division. (D)</p> Signup and view all the answers

What do halophiles require to thrive in their environment?

<p>High salt concentrations. (D)</p> Signup and view all the answers

Which of the following is NOT a method of physical microbial control?

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

What is the significance of the Phenol coefficient in disinfectant testing?

<p>It compares the effectiveness of a disinfectant to phenol. (C)</p> Signup and view all the answers

Which microorganism was historically significant for the discovery of antibiotics?

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

What distinguishes broad-spectrum antimicrobial drugs from narrow-spectrum drugs?

<p>Broad-spectrum targets a wide variety of pathogens. (A)</p> Signup and view all the answers

Which factor does NOT influence the generation time of bacteria?

<p>Presence of antibiotics (A)</p> Signup and view all the answers

During the formation of biofilms, what role does EPS play?

<p>It provides structural stability. (C)</p> Signup and view all the answers

Which of the following best describes the difference between sterilization and sanitation?

<p>Sterilization kills all microorganisms, while sanitation reduces their numbers. (B)</p> Signup and view all the answers

Which microbial control method is described as utilizing extreme pressure?

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

What distinguishes BSL-4 laboratories from lower levels of biosafety?

<p>Handling of highly pathogenic organisms. (B)</p> Signup and view all the answers

The mechanism of action of most disinfectants generally involves which of the following?

<p>Destruction of the cell membrane. (A)</p> Signup and view all the answers

Which of the following is NOT a characteristic of mesophiles?

<p>Resistance to very high temperatures. (C)</p> Signup and view all the answers

Which antimicrobial drug class is specifically known for being used against fungal infections?

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

What best defines the term 'selective toxicity' in antimicrobial therapy?

<p>It harms pathogens while minimizing damage to host cells. (C)</p> Signup and view all the answers

Which method of measuring microbial growth is least likely to determine the total viable count?

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

What defines the growth phase in which microorganisms are adapting to their new environment and not yet dividing?

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

Which of the following describes a method used to control microbial growth through the application of high temperatures?

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

What is the role of extracellular polymeric substances (EPS) in biofilm formation?

<p>Stabilizing the biofilm structure (C)</p> Signup and view all the answers

Which group of microorganisms can thrive in highly acidic environments?

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

What is one of the main distinctions between sterilization and disinfection in microbial control?

<p>Sterilization kills all forms of microbial life; disinfection does not. (D)</p> Signup and view all the answers

Which antimicrobial characteristic refers to its ability to specifically target bacteria without harming human cells?

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

What does the term 'quorum sensing' refer to in microbial communities?

<p>The communication among bacteria to coordinate behavior based on population density (C)</p> Signup and view all the answers

Which of the following is a characteristic of a facultative anaerobe?

<p>Prefers oxygen but can grow without it (C)</p> Signup and view all the answers

Which method of microbial control relies on the growth of organisms in a controlled environment to maintain a constant nutrient supply?

<p>Chemostat method (C)</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 daughter cells.

Generation Time

The time it takes for a bacterial population to double.

Growth Curve

A graphical representation of bacterial growth over time, with distinct phases like lag, log, stationary, and death phases.

Sterilization

The process of eliminating all forms of microbial life, including bacteria, viruses, and spores.

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Disinfection

The process of reducing or eliminating the number of pathogenic microbes, but not necessarily all microbes.

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Microbial Death Curve

A graph showing the rate at which microbes die over time when exposed to a control method.

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Selective Toxicity

The ability of an antimicrobial drug to kill or inhibit the growth of a pathogen without harming the host cells.

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Antimicrobial Drug

A substance used to kill or inhibit the growth of microbes.

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Chemostat

A device for growing microorganisms under controlled conditions, maintaining constant growth rate.

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Microbiological Growth

Encompasses the growth, testing, and recording of bacteria and other microbes.

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Z ring assembly

The formation of a ring-like structure made of the protein FtsZ during binary fission, which constricts the cell membrane and divides the cell into two daughter cells.

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Lag phase

The initial phase of bacterial growth where cells are adapting to the new environment and preparing for rapid growth, characterized by little to no increase in cell number.

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Log phase

The exponential growth phase of bacteria where cells divide rapidly at a constant rate, resulting in a steep increase in population.

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Stationary phase

The phase of bacterial growth where the growth rate slows down to a standstill due to limited resources and accumulating waste products.

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Death phase

The phase of bacterial growth where the number of viable cells decreases rapidly as environmental conditions become unfavorable and cells die.

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Biofilm formation

A multi-step process where bacteria attach to a surface, form a matrix of extracellular polymeric substances (EPS), and communicate through quorum sensing.

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Quorum sensing

A form of bacterial communication where cells release signaling molecules to sense the population density and coordinate collective behaviors.

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Obligate anaerobe

A microbe that cannot survive in the presence of oxygen and can only grow in oxygen-free environments.

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Autoclave

A high-pressure steam sterilizer used to eliminate all microorganisms, achieving sterilization.

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Growth Curve Phases

The different stages of bacterial growth, including lag, log (exponential), stationary, and death phases.

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Media used for bacterial growth

Different types of media used to grow bacteria, including selective, differential, and enriched media.

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Sterilization vs. Disinfection

Sterilization eliminates all microbes, while disinfection reduces harmful microbes.

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Biofilm

A complex, organized community of bacteria that adhere to a surface and are encased in a matrix of extracellular polymeric substances (EPS).

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Study Notes

Chapter 9 Review

  • Binary fission: Steps and Z ring assembly
  • Generation time: Calculating population time (general; no calculator needed)
  • Growth curve: Stages include Lag, Log, Stationary, and Death phases. Sustainable growth can occur in a chemostat.
  • Growth measurement methods: Microscopic, Fluorescent, Coulter, Viable count (CFU), Optical Density (OD), Membrane filtration, and MPN methods. Understand how each method works, when it is used, and its limitations.
  • CFU counting: Pour plate vs. spread plate methods, and count ranges.
  • Alternate growth patterns: Biofilms, steps of biofilm formation, extracellular polymeric substance (EPS), quorum sensing.
  • Environmental factors: Impact on generation time and growth are oxygen (aerobes, anaerobes, facultative), temperature (thermophiles, psychrophiles, mesophiles), pH (acidophiles, neutrophiles), osmotic pressure and barometric pressure.

Chapter 13 Review

  • Sterilization vs. Disinfection vs. Antisepsis vs. Degerming vs. Sanitation: Understand the differences in each.
  • Clean in clinic: Critical, semi-critical, and noncritical items classification
  • Chemical control: Phenolics, heavy metals, halogens, alcohols, surfactants, bisbiguanides, alkylating agents, peroxygens. When are they used? What are examples and limitations for each? Pharmaceutical, cosmetics, and food preservatives.
  • Physical control: Heat (dry and moist), autoclaves, pasteurization, refrigeration, freezing, desiccation, lyophilization, water activity, radiation (ionizing and non-ionizing), filtration (membrane, HEPA), pressure, and sonication.
  • Disinfectant/preservative testing: Phenol coefficient, disk diffusion, use-dilution, and in-use tests.

Chapter 14 Review

  • Brief history of antimicrobials: Scientists including Ehrlich, Klarer, Mietzch, Domagk, Fleming, Hodgkin, and Waksman - key contributions to the field.
  • Narrow vs. broad spectrum: Antimicrobials, understanding the target pathogens, and dosing.
  • Antimicrobial drugs: Study of individual drugs, their mechanism of action (MOA), targeted pathogens, and adverse effects.
  • Common uses, challenges, and adverse effects: Different classes of antimicrobials including antifungals, antiprotozoans, antihelminthics, and antivirals (ART inhibitors). Inhibition of bacterial cell walls, proteins, membranes, metabolic pathways, nucleic acids, and ATP synthesis are pathways of action.
  • Antibiotic resistance: Mechanisms, and examples. ESKAPE pathogens (VRE, VRSA, VISA, MRSA, ESBLs, CRE, MDR-TB, XDR-TB)
  • Testing for efficacy: Kirby-Bauer (zone of inhibition), and dilution tests (MIC, MBC, and Etest).
  • Current antibiotic discovery: Understand the different options, targets, and techniques.

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Exam #3 Review Ch. 9, 13, & 14 Review PDF

Description

This quiz covers important concepts from Microbiology chapters 9 and 13, focusing on microbial growth mechanisms, laboratory practices, and environmental influences on growth. Test your understanding of binary fission, growth curves, and sterilization techniques.

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