exam 2 Flashcards by Maggie Coyle

What is the primary requirement for bacterial colonization?
a) The ability to evade antibiotics
b) Stable attachment to the host and/or a replication rate that equals or exceeds host removal rate
c) The production of toxins
d) The presence of a thick capsule

b) Stable attachment to the host and/or a replication rate that equals or exceeds host removal rate

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Which of the following bacteria is transmitted via a tick bite?
a) Mycobacterium tuberculosis
b) Vibrio cholerae
c) Borrelia burgdorferi
d) Helicobacter pylori

c) Borrelia burgdorferi

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What structure provides swimming motility through fluids?
a) Pili
b) Flagellum
c) Adhesins
d) Biofilm

b) Flagellum

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Which of the following is NOT a bacterial immune evasion strategy?
a) Preventing opsonization
b) Modifying MAMPs to avoid PRR detection
c) Increasing host immune response
d) Killing phagocytes

c) Increasing host immune response

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What bacterial component is recognized by TLR4?
a) Peptidoglycan
b) Lipopolysaccharide (LPS)
c) Flagellin
d) CpG-rich DNA

b) Lipopolysaccharide (LPS)

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How does Yersinia pestis modify lipid A to evade immune detection in human hosts?
a) It removes all lipid A components
b) It changes lipid A to a tetra-acylated form
c) It increases LPS production
d) It uses a different endotoxin

b) It changes lipid A to a tetra-acylated form

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What is the primary function of bacterial capsules?
a) Enhancing motility
b) Facilitating adhesion
c) Interfering with complement activation and phagocytosis
d) Producing toxins

c) Interfering with complement activation and phagocytosis

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What is the role of bacterial secretion systems?
a) Facilitate nutrient absorption
b) Deliver effector proteins into host cells
c) Form biofilms
d) Protect bacteria from dehydration

b) Deliver effector proteins into host cells

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Which bacterial component allows for antigenic variation?
a) Flagella
b) Capsule
c) Pili
d) Peptidoglycan

c) Pili

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How do bacteria sense their environment?
a) Through biofilm formation
b) By using two-component regulatory systems
c) By secreting toxins
d) Through passive diffusion

b) By using two-component regulatory systems

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(T/F) Pili can be involved in both adhesion and DNA transfer.

True

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(T/F) Biofilms provide no protection against antibiotics.

False

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(T/F) Nutrient acquisition is a key factor for bacterial colonization.

True

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(T/F) LPS structural variation affects immune recognition.

True

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(T/F) TLRs recognize bacterial MAMPs and activate immune responses.

True

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(T/F) S. pneumoniae’s capsule is essential for immune evasion and pathogenesis.

True

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(T/F) Bacterial quorum sensing controls gene expression in response to population density.

True

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(T/F) Type III secretion systems inject bacterial proteins directly into host cells.

True

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(T/F) Iron sequestration is a bacterial defense mechanism against host immune responses.

True

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(T/F) Some bacteria can survive inside macrophages by preventing phagolysosome fusion.

True

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(Short) Explain how bacterial motility aids in colonization and pathogenesis.

bacteria can move to new environments
evade host immune defenses
establish infections

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(Short) What is the role of adhesins in bacterial attachment to host cells?

allow bacteria to adhere to host cells

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(Short) How do bacteria acquire iron from the host, and why is iron important?

siderophores (transferrin)
direct secretion systems (heme)

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(Short) Describe the immune evasion strategy of antigenic mimicry and provide an example.

hylauronic acid is found in the capsule of s. pyogenes and also in the host cell as a part of the extracellular membrane

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(Short) How do phagocytes neutralize bacterial infections, and how do some bacteria evade this process?

(macrophage, neutrophils, dendritic cells) use PRRs (TLRs) to recognize PAMPs (LPS, peptidoglycan, flagellin) capsules prevent phagocytosis (s. pneumoniae)

(Short) Explain the significance of quorum sensing in bacterial virulence.

- recognition of virulence factors - exotoxins (v. cholerae making cholera toxin) - biofilm formation - secretion of hydrolytic enzymes

(Short) How do bacterial biofilms contribute to antibiotic resistance?

- physical barrier to antibiotic penetration - bacterial heterogeneity and dormancy - altered microenvironment within biofilm - horizontal gene transfer

(Short) What is the role of Type IV secretion systems in bacterial pathogenesis?

- deliver effector proteins to host cell (aid immune response) - horizontal gene transfer - immune evasion and inhibition - biofilm formation

(Short) How does complement evasion enhance bacterial survival?

- prevention of complement activation - protection from opsonization - resistance to MAC - complement receptor mimicry - biofilm formation

(Short) Describe the process of intracellular survival strategies used by certain pathogens.

- escape from phagosome/endosome - inhibition of phagolysosome fusion - nutrient acquisition from host

Match the bacterial structures with their function: 1. Flagellum 2. Pili 3. Siderophores 4. Biofilm 5. Capsule 6. Type III Secretion System 7. Quorum Sensing Molecules 8. Two-Component Regulatory System 9. Outer Membrane Proteins 10. Lipopolysaccharides (LPS) a) Iron acquisition b)Protective community structure c) Motility d) Adhesion and DNA transfer e) Immune evasion f) Direct protein injection into host cells g) Cell-density dependent gene regulation h) Environmental signal sensing i) Host immune evasion and nutrient uptake j) Endotoxin triggering immune responses

flagellum:motility pili:adehsion and DNA transfer siderophores:iron acquisition biofilm:protective community structure capsule:immune evasion type iii secretion systems:direct protein injection into host cells quorum sensing molecules:cell-density dependent gene regulation two-component regulatory system:environmental signal sensing outer membrane proteins:host immune evasion and nutrient uptake lipopolysaccharides:endotoxin triggering immune responses

(Short) Describe the difference between Gram-positive and Gram-negative pilus assembly.

gram (+) - following translation, pilin proteins must be exported through the membrane - sortase cleaves LPXTG and pilus gets oligomerized - pilus is added to PG precursor lipid ii and then incorporated into cell wall gram (-) - pilus are assembled and anchored in the outer membrane - pilin subunits are exported into the periplasm - chaperones traffic pilins to dedicated outer membrane proteins

(Short) What are the stages of immune response?

1. Recognition 2. Activation 3. Response 4. Memory

What is the primary function of bacterial toxins? a) Aid in photosynthesis b) Disrupt host cell function and homeostasis c) Help bacteria in aerobic respiration d) Promote host cell regeneration

b) Disrupt host cell function and homeostasis

Which of the following is a neurotoxin? a) Botulinum toxin b) Hemolysin c) Phospholipase d) Superantigen

a) Botulinum toxin

Superantigens primarily cause: a) Direct destruction of red blood cells b) Excessive cytokine release c) Inhibition of phagocytosis d) DNA replication errors

b) Excessive cytokine release

Type III toxins, also known as AB toxins, function by: a) Directly lysing host membranes b) Binding host cell receptors and entering the cytoplasm c) Neutralizing reactive oxygen species d) Altering host antigen presentation

b) Binding host cell receptors and entering the cytoplasm

Which bacterial structure is often targeted by antibiotics? a) Ribosomes b) Golgi apparatus c) Mitochondria d) Lysosomes

a) Ribosomes

What is the primary function of neutrophil extracellular traps (NETs)? a) Degrade bacterial cell walls b) Trap and kill bacteria using DNA and toxic enzymes c) Prevent bacterial motility d) Facilitate bacterial replication

b) Trap and kill bacteria using DNA and toxic enzymes

Listeria monocytogenes uses which mechanism to move within host cells? a) Actin polymerization b) Flagellar rotation c) Toxin secretion d) Capsule formation

a) Actin polymerization

What enzyme detoxifies reactive oxygen species in bacteria? a) Catalase b) DNA polymerase c) Ligase d) Helicase

a) Catalase

Which bacterial pathogen is known for antigenic variation? a) Neisseria gonorrhoeae b) Escherichia coli c) Bacillus subtilis d) Clostridium difficile

a) Neisseria gonorrhoeae

What is the function of IgA protease? a) Degrades host IgA antibodies to evade immune detection b) Enhances bacterial adhesion c) Induces apoptosis in host cells d) Neutralizes bacterial toxins

a) Degrades host IgA antibodies to evade immune detection

(T/F) Tetanus toxin and botulinum toxin both affect the nervous system.

True

(T/F) Cholesterol-dependent cytolysins form pores in host cell membranes.

True

(T/F) Hemolysins always play a significant role in bacterial pathogenesis.

False

(T/F) Staphylococcus aureus only causes skin infections.

False

(T/F) Exotoxins are always made of proteins.

True

(T/F) Neisseria gonorrhoeae can survive despite a strong neutrophil response.

True

(T/F) Listeria monocytogenes uses actin polymerization for intracellular movement.

True

(T/F) Phagocytosis is the only mechanism neutrophils use to kill bacteria.

False

(T/F) Superantigens can trigger excessive immune responses leading to shock.

True

(T/F) Antigenic variation allows bacteria to evade the adaptive immune system.

True

(Short) Explain how NETs help neutrophils trap pathogens.

NETs are like webs that ensnare and kill pathogens into the neutrophil

(Short) Describe two mechanisms bacteria use to evade phagocytosis.

altered surface structures (LPS) detoxify reactive oxygen species (catalase)

(Short) What is the role of phospholipases in bacterial virulence?

- host cell membrane disruption - evasion of host immune responses - biofilm formation and persistance

(Short) How does antigenic variation help bacteria evade the immune system?

frequent alteration of surface proteins so a molecule may remain unrecognizable

(Short) What distinguishes Type I, Type II, and Type III toxins?

Type I: bind to host cell, act extracellularly (superantigens) Type II: act on eukaryotic cell membranes (pore-forming toxins) Type III: two subunit toxins (AB) (cholera toxin)

(Short) Explain how Listeria monocytogenes spreads between host cells.

- enters through endocytosis - escapes phagosome into cytosol with help from listeriolysin O - surface protein ActA which uses actin molecules to make a "comet tail"

(Short) How do some bacteria detoxify reactive oxygen species?

- superoxidase dismutase - catalase - peroxiredoxins

(Short) What role does fibronectin binding play in bacterial immune evasion?

- facilitates attachment and colonization of host tissues - glycoprotein found on extracellular matrix

(Short) Describe the function of invasins in bacterial infections.

- facilitating host cell attachment - inducing host cytoskeletal rearrangement - promoting phagocytosis-like invasion - avoiding immune detection - l. monocytogenes InIAB

(Short) How does the Type IV secretion system contribute to bacterial pathogenesis?

- effector protein delivery to host cells (enable disruption of host immune responses) - dna transfer and horizontal gene transfer - immune evasion

Match the following toxins to their corresponding bacteria: a) Cholera toxin - _______________ b) Tetanus toxin - _______________ c) TSST-1 - _______________ d) Listeriolysin O - _______________ e) Superantigen - _______________

a) Vibrio cholerae b) Clostridium tetani c) Staphylococcus aureus d) Listeria monocytogenes e) Staphylococcus aureus or Streptococcus pyogenes

Match the following bacterial species with their primary virulence strategy: a) Neisseria gonorrhoeae - _______________ b) Listeria monocytogenes - _______________ c) Legionella pneumophila - _______________ d) Mycobacterium tuberculosis - _______________ e) Salmonella enterica - _______________

a) Antigenic variation and pili-mediated adhesion b) Intracellular survival and actin-based motility c) Intracellular survival and manipulation of host cell vesicles d) Intracellular survival and immune evasion in macrophages e) Type III secretion system and invasion of host cells

Match the following immune evasion strategies to their mechanisms: a) Antigenic variation - _______________ b) IgA protease - _______________ c) Intracellular replication - _______________ d) Phagosome escape - _______________ e) Host mimicry - _______________

a) Changing surface antigens to evade immune detection b) Degradation of secretory IgA antibodies c) Survival and multiplication within host cells d) Escape from the phagosome into the cytoplasm e) Mimicking host molecules to avoid immune detection

Match the bacterial enzyme to its function: a) Catalase - _______________ b) Hemolysin - _______________ c) DNase - _______________ d) Coagulase - _______________ e) Phospholipase - _______________

a) Breaks down hydrogen peroxide (H₂O₂) into water and oxygen b) Breaks down red blood cells (RBCs) and releases hemoglobin c) Degrades DNA d) Promotes blood clot formation e) Breaks down phospholipids in cell membranes

Match the bacterial component to its immune function: a) Capsule - _______________ b) LPS - _______________ c) Flagella - _______________ d) Pili - _______________ e) Peptidoglycan - _______________

a) Prevents phagocytosis b) Triggers immune responses and inflammation c) Mediates motility and immune recognition d) Facilitates adhesion and immune evasion e) Activates innate immune receptors

exam 2 Flashcards

(68 cards)