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Foundations Exam 2 > Bacteria > Flashcards

Bacteria Flashcards

1
Q

Function of human microbiome

A

Development of immune system, colonization resistance (presence of commensals prevent growth of pathogens), and nutritional value (vit B and K)

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2
Q

Eukaryotic characteristics

A

Nucleus, chromosomes composed of strands of DNA (diploid genome), membrane bound organelles present, 80S (60S+40S) ribosomes, cytoplasmic membrane contains sterols, cell wall present in fungi and plants but otherwise absent, sexual and asexual reproduction, respiration via mitochondria

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3
Q

Prokaryotic characteristics

A

No nucleus, chromosome = single, circular DNA composing haploid genome, membrane bound organelles absent, 70S(50S+30S) ribosome, cytoplasmic membrane does not contain sterols, cell wall made of peptidoglycan, asexual reproduction, and respiration via cytoplasmic membrane

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4
Q

30S subunit of prokaryotic ribosome susceptible to antibiotics…..

A

Aminoglycosides and tetracyclines

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5
Q

50S subunit of prokaryotic ribosome susceptible to antibiotics…

A

Macrolides, clindamycin

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6
Q

Gram positive

A

Thick peptidoglycan layer, stains purple, one membrane bilayer (for E production, membrane potential, and transport), teichoic acid, no LPS, no F-pili

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7
Q

Gram negative

A

Thin peptidoglycan, 2 membranes, no teichoic acid, LPS, F-pili

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8
Q

Peptidoglycan layer

A

Rigid, mesh-like; polymer of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) (lined by beta-1,4 glycosidic bond); tetrapeptide attached to NAM

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9
Q

Cross-linking of peptidoglycan layer mediated by..

A

Transpeptidase and carboxypeptidase (penicillin-binding proteins)

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10
Q

Lysozyme interferes with….in peptidoglycan layer formation

A

beta-1,4 glycosidic bond

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11
Q

Penicillins and cephalosporings interfere with…..in peptidoglycan layer formation

A

Tetrapeptide formation

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12
Q

Vancomycin interferes with….in peptidoglycan layer formation

A

Cross-linking formation

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13
Q

Two bilayers in gram-negative

A

Outer - permeability barrier
Porin proteins - passage of small hydrophilic molecules
Secretory systems
LPS
Inner membrane - E production, membrane potential, and transport

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14
Q

Periplasmic space

A

Transport proteins, hydrolytic enzymes that break down macromolecules; gram-negative contains virulence factors (collagenase, protease, hyaluronidase, and beta-lactamase)

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15
Q

Lipopolysaccharide

A

Lipid A - anchors LPS to membrane (toxic)
Core polysaccharide - composed of various sugars
O-antigen - polysaccharide repeat; elicits host immune response; used for serotyping

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16
Q

LPS stimulates…

A

Proinflammatory cytokines, activation of complement cascade and cause histamine release, B cell mitogen, recognized by host Toll-like receptor 4 (TLR4)

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17
Q

Capsule

A

Glycocalyx; composed of polysaccharides (target of certain vaccines); protein capsules rare (B. anthracis); encapsulated = smooth, non-encapsulated - rough; major virulence factor (adherence, antiphagocytic)

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18
Q

Function of pili/fimbrae

A

Adherence; motility (twitching-grappling hook-like); major virulence factor in certain bacteria

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19
Q

F pili

A

Sex pili; specialized, longer, fimbrae used to transfer DNA via conjugation; encoded in F plasmid, specific to gram-negative

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20
Q

Flagella

A

Motility, propulsion; rigid; chemotaxis; proton motive force powers; highly antigenic (TLR-5)

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21
Q

Monotrichous flagella

A

Single polar flagellum

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22
Q

Lophotricus flagella

A

Multiple polar flagella

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23
Q

Peritrichous flagella

A

Multiple flagella all over bacteria

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24
Q

Amphitrichous flagella

A

Polar flagellum on each end

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25
Run and tumble maneuver of flagella
Counterclockwise - positive - run; clockwise - negative - tumble (no longer conducive to movement - allows them to change directions)
26
Bacterial chromosome
Circular; haploid; polycistronic (multiple genes on single transcript)
27
Bacterial plasmid
Circular; haploid; extrachromosomal element; replicates independent of chromosomes; can be transferred to another bacteria via F-pilus
28
Coccus
Round
29
Bacillus
Rod
30
Coccobacillus
Oval
31
Diplococcus
2 circles
32
Spirochete
Corkscrew
33
Vibrio
Comma; boomerang
34
Streptococcus
Line of circles
35
Streptobacillus
Line of rods
36
Staphylococcus
Cluster of circles
37
Endospores
Produced by Bacillus and Clostridium gram-positive under favorable environmental conditions (survival mechanisms); actively growing = vegetative; endospores are considered dormant (dehydrated multishelled structure, contains one full chromosome, high amounts of dipicolinic acid and calcium); highly resistant to heat, radiation, pH, pressure, chemicals
38
Binary fission
Cell enlarges, chromosome replication is initiated at membrane, membrane synthesis, peptidoglycan synthesis (penicillins, cephalosporins), and cell division link, during DNA replication, supercoiled form and topoisomerase relaxes (quinolones target these), two daughter cells form
39
Bacterial growth curve
Lag phase, exponential phase, stationary phase, decline phase
40
Lag phase
Bacteria acclimate to environment (gene regulation, production of metabolites); no significant replication
41
Exponential phase
Bacterial growth and division at same rate; doubling time differs amongst bacteria
42
Stationary phase
Nutrients depleted; metabolic toxins high; cell division equals cell death
43
Decline phase
No bacterial growth; cells dying
44
Requirements for bacterial growth
Carbon and nitrogen source, energy source, water
45
Bacteria utilize different carbon sources and produce different end products, enabling.....
For the differentiation and identification of specific bacteria
46
Fermentation
Process where organic molecule acts as an electron donor and one or more of its organic products act as a final electron acceptor, resulting in anaerobic energy production; major tool utilized to differentiate and identify bacteria
47
MacConkey Agar
Tests for ability to ferment lactose
48
ETC localized....
To plasma membrane of bacterial cells
49
How does the ETC differ from mitochondrial ETC?
1. ) Electrons may enter ETC at multiple points and through multiple terminal oxidases 2. ) Shorter, so less E production 3. ) More complex with both aerobic and anaerobic pathways
50
Tools used to differentiate and identify bacteria
Oxidase test and nitrate reduction test
51
Obligate aerobe
Needs oxygen to grow (will grow on top since that's where it will get most oxygen); has enzymes superoxide dismutase and catalase to help negate ROS
52
Microaerophile
Requires certain percentage of oxygen
53
Aerotolerant anaerobe
Oxygen doesn't matter
54
Facultative anaerobe
Prefers oxygen but can grow without; enzymes to negate ROS present
55
Obligate anaerobe
Oxygen is toxic; does not contain enzymes to negate ROS
56
Iron acquisition
Iron is essential for bacterial growth so bacteria secrete siderophores that chelate iron with high affinity (steal iron) and hemolysins lyse erythrocytes (can be virulence factors)
57
Capnophile
High CO2
58
Halophile
High salt
59
Mesophile
Optimal growth at 20-45 celcius
60
Obligate intracellular bacteria
Replicate inside host cells
61
Facultative intracellular bacteria
Prefer to replicate inside host cells but can replicate outside host cells
62
Extracellular bacteria
Replicate outside host cells
63
Pathogen
Organism that causes disease
64
Opportunistic pathogen
Organism that causes disease in immunocompromised individuals
65
Infectious disease
Disease caused by an organism
66
Virulence
Ability of an organism to cause disease
67
Virulence factor
Trait that enhances disease by helping survival of bacteria
68
Contagious disease
Transmissibility of disease from individual to individual
69
Virulence factors/mechanisms
Antigenic variation, adhesins, biofilm, chemotaxis, capsule, lipases, motility, nucleases, proteases, siderophores, and toxins
70
Pathogenesis
1. ) Entry into host 2. ) Adherence via adhesins 3. ) Colonization, invasion, growth (toxins and effector proteins, siderophores, secretion systems, motility, endospore) 4. ) Immune evasion (biofilm, toxins and effector proteins, secretion systems)
71
Toxins of pathogenesis
1. ) Endotoxin (LPS) - glycolipid that elicits robust immune response 2. ) Exotoxin - protein that is released from bacteria cell
72
Intoxication
A toxin is directly causing the disease
73
Infection
The pathogen is causing the disease
74
Pathogenesis immune evasions
1. ) Complement evasion (Staph aureus) 2. ) antibody evasion/destruction (protein A, IgA protease, antigenic variation) 3. ) Phagocytosis evasion 4. ) Intracellular behavior and cell-to-cell spread 5. ) Biofilm production 6. ) pH survival
75
Phagocytosis evasion methods
``` Resist ROS Prevent phagosome from fusing to lysosome Escape from phagosome Prevent phagocytosis Kill phagocytes ```

Foundations Exam 2 (8 decks)

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