Biology Chapter 1-3 Overview
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Questions and Answers

What is a major disadvantage of using broad-spectrum antimicrobials?

  • They are effective against a wide range of pathogens.
  • They require identification of the pathogen.
  • They tend to be less effective in treating acute diseases.
  • They can lead to dysbiosis by disrupting normal microbiota. (correct)

What defines synergistic interaction among antimicrobial medications?

  • The medications have no effect on each other.
  • The medications are identical in function.
  • The medications counteract each other's effects.
  • The medications enhance each other's effects. (correct)

How does penicillin primarily exert its antibacterial effect?

  • It inhibits enzymes responsible for cell wall production. (correct)
  • It interferes with DNA replication.
  • It blocks the synthesis of cell membranes.
  • It disrupts protein synthesis.

What is a characteristic of narrow-spectrum antimicrobials?

<p>They are less likely to disrupt normal microbiota. (B)</p> Signup and view all the answers

Which mechanism allows bacteria to resist the effects of antibiotics through genetic sharing?

<p>Horizontal gene transfer. (A)</p> Signup and view all the answers

What does the term Minimum Inhibitory Concentration (MIC) refer to?

<p>The lowest concentration of drug that prevents bacterial growth. (A)</p> Signup and view all the answers

Which of the following statements is true about the Kirby-Bauer disc diffusion test?

<p>It assesses susceptibility based on the diffusion of antibiotics in agar. (D)</p> Signup and view all the answers

What common issue arises with the interpretation of Minimum Inhibitory Concentration (MIC) results?

<p>It often indicates whether a bacteria is cidal or static. (A)</p> Signup and view all the answers

Which statement describes the difference between bacteriostatic and bactericidal chemicals?

<p>Bacteriostatic chemicals inhibit growth reversibly, while bactericidal chemicals kill irreversibly. (C)</p> Signup and view all the answers

What is the primary purpose of pasteurization?

<p>To briefly heat food to reduce spoilage and eliminate pathogens. (B)</p> Signup and view all the answers

Which biosafety level involves pathogens that are lethal but have treatment options?

<p>Bio Safety 3 (B)</p> Signup and view all the answers

Which chemical classification is designed to destroy all microbes, including endospores, but not prions?

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

What does selective toxicity refer to in the context of antibiotics?

<p>The design of drugs that target the pathogen while minimizing damage to the host. (D)</p> Signup and view all the answers

Which disinfectant is characterized by destroying most viruses, fungi, and vegetative cells but does not affect endospores?

<p>Intermediate-level disinfectant (B)</p> Signup and view all the answers

What is the therapeutic index in pharmacology?

<p>The ratio between the lethal dose and the effective dose of a drug. (C)</p> Signup and view all the answers

What is the mode of action for bacteriostatic agents?

<p>They inhibit bacterial growth without killing the organisms. (B)</p> Signup and view all the answers

What is the main reason antimicrobials are more effective against Gram-positive bacteria compared to Gram-negative bacteria?

<p>Antimicrobials target peptidoglycan, which is more abundant in Gram-positive bacteria. (B)</p> Signup and view all the answers

Which of the following statements about archaeal cell walls is true?

<p>They may consist of pseudomurein instead of peptidoglycan. (B)</p> Signup and view all the answers

What role does lysozyme play in targeting bacterial cells?

<p>It destroys glycan chains in the cell wall. (B)</p> Signup and view all the answers

What type of structure is a capsule in bacterial cells?

<p>A well-organized layer made of polysaccharides. (A)</p> Signup and view all the answers

How do flagella aid in bacterial locomotion?

<p>By spinning in a rotary fashion. (D)</p> Signup and view all the answers

Which type of bacterial flagellation is characterized by a single flagellum?

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

What structure is primarily responsible for the stability of archaeal cell membranes?

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

What is a common function of both the slime layer and capsules in bacteria?

<p>They help in the attachment to surfaces. (D)</p> Signup and view all the answers

Flashcards

Broad-spectrum antibiotic

A type of antibiotic that works against a wide range of bacteria.

Narrow-spectrum antibiotic

An antibiotic that affects a limited range of bacteria.

Antibiotic combinations: Synergistic

When two or more antibiotics work together to enhance each other's effectiveness.

Antibiotic combinations: Antagonistic

When two or more antibiotics interfere with each other, reducing their effectiveness.

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Penicillin MOA

Penicillin works by blocking enzymes that bacteria use to build their cell walls.

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Antibiotic Resistance (Mechanism example)

Bacteria can develop resistance to antibiotics by mutating or gaining genes that make them resistant.

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Kirby-Bauer test

A lab test used to determine if a bacteria is susceptible, intermediate, or resistant to a specific antibiotic.

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Minimum Inhibitory Concentration (MIC)

The lowest concentration of an antibiotic that prevents the growth of bacteria.

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Decontamination

Reducing pathogens to a safe level for handling.

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Sanitation

Reducing microbial population to meet health standards.

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Pasteurization

Brief heating to reduce spoilage and pathogens.

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Selective toxicity

Damages microbes more than human host.

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Therapeutic index

Ratio of toxic dose (50%) to effective dose (50%).

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Bacteriostatic

Inhibits bacterial growth, reversible.

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Bactericidal

Kills bacteria, irreversible.

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Bio safety level 3

Aerosol-transmitted pathogens, potentially lethal with treatment

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What makes archaeal cell walls different from bacterial cell walls?

Archaeal cell walls lack peptidoglycan (a major component of bacterial cell walls) and instead have a similar structure called pseudomurein. They can also have S-layers made of proteins or glycoproteins, but not a true outer membrane like bacteria.

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How do antimicrobials like penicillin target bacteria?

Penicillin specifically targets the peptidoglycan layer in bacterial cell walls, preventing the cross-linking of glycan chains. This disrupts the cell wall's integrity, leading to lysis.

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What are S-layers?

S-layers are sheets of protein or glycoprotein that self-assemble into a highly organized layer found in some archaea. They provide structural support and protection.

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Why is penicillin more effective against Gram-positive bacteria?

Penicillin's effectiveness is hampered by the outer membrane of Gram-negative bacteria, which acts as a barrier. Gram-positive bacteria lack this outer membrane, making them more vulnerable to penicillin's action.

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Lysozyme: What's its role?

Lysozyme is an enzyme found in tears and saliva that breaks the bonds between N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) in bacterial peptidoglycan.

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Capsule

A well-organized, tightly bound layer made of polysaccharides that surrounds some bacteria. It's difficult to remove and protects the bacterium.

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Slime layer

A loosely organized layer of polysaccharides that surrounds some bacteria. It can be easily washed away.

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Flagella

Hair-like structures used for movement by bacteria. They are too thin to see with a light microscope.

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Study Notes

Chapter 1 - Introduction

  • Robert Hooke described the common bread mold
  • Coined the term "cell"
  • Antony van Leeuwenhoek ground lenses to view clothes, then investigated a drop of lake water
  • Described "wee animalcules" and "cavorting beasties"
  • Louis Pasteur discovered that air has microorganisms
  • Robert Koch established a connection between bacteria and disease
  • Koch's postulates:
    • Microorganisms must be present in every case of the disease but absent from healthy organisms
    • The suspected microbe must be isolated and grown in a pure culture
    • The same disease results when the isolated microbe is put into a healthy host
    • The same microbe must be isolated from the new host
  • Classification of microbes (comparing 16S RNA sequence): Bacteria, Archaea, and Eukarya
  • Prokaryotes lack a membrane-bound nucleus or organelles
  • Eukaryotes have organelles and a nucleus

Chapter 2-3 - Microscopy and Cell Structure

  • Principles of light microscopy: bright-field, dark-field, phase-contrast, fluorescence, and confocal microscopy
  • Light passes through a specimen and magnifying lenses
  • Electron microscopy uses electrons instead of light, providing higher resolution and allowing for examination of internal structures

Additional Information

  • Simple stains use a single stain to visualize cell morphology (size, shape, arrangement)
  • Differential stains differentiate cell types (Gram-positive vs. Gram-negative, acid-fast)
  • Endospore stains highlight dormant, resistant structures in some bacteria
  • Bacterial cell walls have unique structures (Gram-positive vs. Gram-negative)
  • Mycoplasma species lack cell walls
  • Archaea have unique cell wall compositions without peptidoglycan
  • Flagella and pili are used for motility. Flagella rotate, pili twitch and glide

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Description

Explore key concepts from Chapters 1 to 3 of Biology, including the discoveries of Robert Hooke and Louis Pasteur on microorganisms, as well as the fundamentals of microscopy and cell structure. This quiz tests your understanding of microbial classification and the principles behind viewing microscopic organisms.

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