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Questions and Answers
A researcher is studying a bacterial species and observes that it readily forms biofilms on catheters. Which of the following structures is MOST likely contributing to this phenomenon?
A researcher is studying a bacterial species and observes that it readily forms biofilms on catheters. Which of the following structures is MOST likely contributing to this phenomenon?
- Capsule
- Slime layer (correct)
- Flagella
- F pili
A microbiologist is trying to identify a Gram-negative bacterial species isolated from a patient with a urinary tract infection (UTI). Antibodies against which of the following structures would be MOST useful for serotyping and identification?
A microbiologist is trying to identify a Gram-negative bacterial species isolated from a patient with a urinary tract infection (UTI). Antibodies against which of the following structures would be MOST useful for serotyping and identification?
- Capsular polysaccharides (correct)
- Pilin
- Spores
- Secretion systems
A bacterium's ability to cause a urinary tract infection (UTI) by ascending the urethra into the bladder is most likely aided by which structure?
A bacterium's ability to cause a urinary tract infection (UTI) by ascending the urethra into the bladder is most likely aided by which structure?
- Capsule
- Fimbriae
- Spores
- Flagella (correct)
Which of the following bacterial structures is MOST directly involved in the transfer of genetic material during conjugation?
Which of the following bacterial structures is MOST directly involved in the transfer of genetic material during conjugation?
A bacterial pathogen inhibits phagocytosis, enhancing its survival within the host. Which structure is MOST likely responsible for this virulence?
A bacterial pathogen inhibits phagocytosis, enhancing its survival within the host. Which structure is MOST likely responsible for this virulence?
A Gram-negative bacterium is found to be injecting proteins into host cells, altering their function to benefit the bacterium. Which structure is MOST likely facilitating this process?
A Gram-negative bacterium is found to be injecting proteins into host cells, altering their function to benefit the bacterium. Which structure is MOST likely facilitating this process?
Under unfavorable environmental conditions, certain bacteria such as Bacillus and Clostridium can form highly resistant structures that allow them to survive for extended periods. These structures are known as:
Under unfavorable environmental conditions, certain bacteria such as Bacillus and Clostridium can form highly resistant structures that allow them to survive for extended periods. These structures are known as:
A researcher discovers a new bacterial species that exhibits strong adherence to human skin cells. Which of the following structures is MOST likely responsible for this adherence?
A researcher discovers a new bacterial species that exhibits strong adherence to human skin cells. Which of the following structures is MOST likely responsible for this adherence?
A bacterium's capsule is composed primarily of:
A bacterium's capsule is composed primarily of:
In Gram-negative bacteria, which structure facilitates the transfer of proteins from the bacterial cell into a host cell during infection?
In Gram-negative bacteria, which structure facilitates the transfer of proteins from the bacterial cell into a host cell during infection?
A researcher is analyzing a bacterial sample and observes cocci arranged in clusters that stain blue/purple with Gram staining. Which of the following presumptive identifications is MOST likely?
A researcher is analyzing a bacterial sample and observes cocci arranged in clusters that stain blue/purple with Gram staining. Which of the following presumptive identifications is MOST likely?
Which of the following methods allows for definitive identification of bacteria by detecting unique surface antigens?
Which of the following methods allows for definitive identification of bacteria by detecting unique surface antigens?
In bacterial nomenclature, what does the first name in the two-name system typically represent?
In bacterial nomenclature, what does the first name in the two-name system typically represent?
Which of the following methods of bacterial classification is MOST closely associated with determining a bacterium’s susceptibility to various antibiotics?
Which of the following methods of bacterial classification is MOST closely associated with determining a bacterium’s susceptibility to various antibiotics?
If a microbiologist observes a bacterial colony displaying a zone of clearing around it on a blood agar plate, what phenotypic characteristic is MOST likely being assessed?
If a microbiologist observes a bacterial colony displaying a zone of clearing around it on a blood agar plate, what phenotypic characteristic is MOST likely being assessed?
A researcher is trying to identify a new strain of E. coli using genotypic methods. Which of the following techniques would be MOST appropriate?
A researcher is trying to identify a new strain of E. coli using genotypic methods. Which of the following techniques would be MOST appropriate?
Which staining technique is often employed as a differential stain, differentiating between bacteria based on their cell wall structure?
Which staining technique is often employed as a differential stain, differentiating between bacteria based on their cell wall structure?
A microbiology lab aims to differentiate bacterial isolates based on their biochemical activities, specifically their ability to ferment different sugars. Which classification method is MOST suitable for this purpose?
A microbiology lab aims to differentiate bacterial isolates based on their biochemical activities, specifically their ability to ferment different sugars. Which classification method is MOST suitable for this purpose?
A researcher is working with a bacterial species that cannot be Gram-stained effectively. Which alternative staining method or test would be MOST appropriate for visualizing these bacteria under a microscope?
A researcher is working with a bacterial species that cannot be Gram-stained effectively. Which alternative staining method or test would be MOST appropriate for visualizing these bacteria under a microscope?
Why is subtyping important in bacterial classification?
Why is subtyping important in bacterial classification?
Which of the following is NOT a function of peptidoglycan in bacterial cells?
Which of the following is NOT a function of peptidoglycan in bacterial cells?
Beta-lactam antibiotics interfere with peptidoglycan synthesis by directly inhibiting which of the following?
Beta-lactam antibiotics interfere with peptidoglycan synthesis by directly inhibiting which of the following?
Lysozyme provides a natural defense against bacterial infections by targeting which structure?
Lysozyme provides a natural defense against bacterial infections by targeting which structure?
Lipopolysaccharide (LPS) is a component of the cell wall in which type of bacteria?
Lipopolysaccharide (LPS) is a component of the cell wall in which type of bacteria?
Which component of LPS is primarily responsible for its toxic effects?
Which component of LPS is primarily responsible for its toxic effects?
The O antigen of LPS is MOST useful for which of the following?
The O antigen of LPS is MOST useful for which of the following?
Which of the following is a characteristic of endotoxins but NOT exotoxins?
Which of the following is a characteristic of endotoxins but NOT exotoxins?
Which of the following is the mechanism of action of vancomycin?
Which of the following is the mechanism of action of vancomycin?
What is the primary function of teichoic acids and lipoteichoic acids in Gram-positive bacteria?
What is the primary function of teichoic acids and lipoteichoic acids in Gram-positive bacteria?
A patient is experiencing fever, hypotension, and disseminated intravascular coagulation (DIC) due to a Gram-negative bacterial infection. Which component of the bacterial cell wall is MOST likely responsible for these symptoms?
A patient is experiencing fever, hypotension, and disseminated intravascular coagulation (DIC) due to a Gram-negative bacterial infection. Which component of the bacterial cell wall is MOST likely responsible for these symptoms?
Flashcards
Capsule
Capsule
A gelatinous layer surrounding bacterial cells that aids in virulence and protection against phagocytosis.
Virulence factor
Virulence factor
Characteristics that enhance the ability of bacteria to cause disease, like capsules that stop phagocytosis.
Capsular polysaccharides
Capsular polysaccharides
Complex sugars in the capsule that can trigger protective antibodies and are used in vaccines.
Flagella
Flagella
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Pili/Fimbriae
Pili/Fimbriae
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Adhesins
Adhesins
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F pili
F pili
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Secretion systems
Secretion systems
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Slime (S) layer
Slime (S) layer
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Spores
Spores
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Peptidoglycan
Peptidoglycan
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Tetrapeptide
Tetrapeptide
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Beta lactams
Beta lactams
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Vancomycin
Vancomycin
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Lysozyme
Lysozyme
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Pattern Recognition Receptors (PRRs)
Pattern Recognition Receptors (PRRs)
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Lipopolysaccharide (LPS)
Lipopolysaccharide (LPS)
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Endotoxin
Endotoxin
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Teichoic acid
Teichoic acid
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Outer polysaccharide
Outer polysaccharide
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Prokaryotes vs. Eukaryotes
Prokaryotes vs. Eukaryotes
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Bacterial Nomenclature
Bacterial Nomenclature
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Subtyping
Subtyping
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Phenotypic Classification
Phenotypic Classification
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Gram Staining
Gram Staining
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Biotyping
Biotyping
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Serotyping
Serotyping
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Genotyping
Genotyping
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Antibiograms
Antibiograms
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Colonial Morphology
Colonial Morphology
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Study Notes
Prokaryotes vs. Eukaryotes
- Prokaryotes lack a nucleus and membrane-bound organelles
- Eukaryotes have a nucleus and membrane-bound organelles
- Prokaryotic DNA is single, circular chromosome
- Eukaryotic DNA is linear, multiple chromosomes
- Prokaryotic cell division is binary fission
- Eukaryotic cell division is mitosis
- Prokaryotic ribosomes are 70S
- Eukaryotic ribosomes are 80S
Bacterial Classification
- Nomenclature: Bacteria are given two names (genus and species)
- Subtyping: Used to distinguish strains or identify new strains
- Example: E. coli O157:H7 is a strain linked to hemolytic uremic syndrome
Bacterial Classification Methods
- Nomenclature: assigning two-part scientific names (genus and species)
- Subtyping: distinguishing strains (e.g., E. coli O157:H7)
- Phenotypic Classification uses observable characteristics, such as
- Macroscopic observations (colony appearance)
- Hemolysis patterns (beta, alpha, gamma)
- Microscopic observations (Gram stain results, cell shape, arrangement)
- Biochemical tests (fermentation of sugars, production of specific end products)
- Serotyping (identifying antigens)
- Genotyping (PCR, hybridization)
Bacterial Structure
- Peptidoglycan (murein): a carbohydrate backbone with amino acids, crucial for bacterial cell walls
- Beta-lactams (penicillins, cephalosporins): interfere with peptidoglycan synthesis
- Vancomycin: inhibits peptidoglycan synthesis (different mechanism)
- Lysozyme: breaks glycosyl bonds, weakens the cell wall.
- Lipopolysaccharide (LPS): an endotoxin found in the outer membrane of Gram-negative bacteria.
Bacterial Structures (cont'd)
- Capsule: a gelatinous layer found in some bacteria that surrounds the cell wall
- Teichoic acids: water-soluble polymers found in the cell walls of Gram-positive bacteria
- Pili/Fimbriae: hair-like appendages found on the surface of bacteria, involved in attachment to surfaces
- Flagella: long, filamentous appendages that allow bacteria to move
- Spores: highly resistant structures formed to survive harsh conditions
Bacterial Virulence Factors
- Secretion systems: used to transfer proteins to eukaryotic cells
- Slime layers: loosely organized layers of polysaccharides that help adhere to surfaces
- Endotoxins (LPS): lipopolysaccharides that are components of Gram-negative cell walls, released when cells die, lead to inflammation and fever
- Exotoxins: proteins secreted by bacteria that are harmful to host cells
- Capsules: protect against phagocytosis
- Flagella, pili: aid in attachment/motility
Gram-Positive vs. Gram-Negative Bacteria
- Gram-positive bacteria have a thick peptidoglycan layer and lack an outer membrane
- Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane containing LPS
- Gram staining is a differential staining technique used to distinguish between the two
Importance of Bacterial Spores
- Highly resistant to heat, chemicals, and other harsh conditions
- Can remain dormant for years, germinating only under favorable conditions
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Description
Comparison of prokaryotic and eukaryotic cells, focusing on key differences like the presence of a nucleus and cell division methods. Exploration of bacterial classification, covering nomenclature and subtyping to identify and distinguish bacterial strains.
