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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
Q

Run and tumble maneuver of flagella

A

Counterclockwise - positive - run; clockwise - negative - tumble (no longer conducive to movement - allows them to change directions)

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26
Q

Bacterial chromosome

A

Circular; haploid; polycistronic (multiple genes on single transcript)

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27
Q

Bacterial plasmid

A

Circular; haploid; extrachromosomal element; replicates independent of chromosomes; can be transferred to another bacteria via F-pilus

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28
Q

Coccus

A

Round

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29
Q

Bacillus

A

Rod

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30
Q

Coccobacillus

A

Oval

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31
Q

Diplococcus

A

2 circles

32
Q

Spirochete

A

Corkscrew

33
Q

Vibrio

A

Comma; boomerang

34
Q

Streptococcus

A

Line of circles

35
Q

Streptobacillus

A

Line of rods

36
Q

Staphylococcus

A

Cluster of circles

37
Q

Endospores

A

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
Q

Binary fission

A

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
Q

Bacterial growth curve

A

Lag phase, exponential phase, stationary phase, decline phase

40
Q

Lag phase

A

Bacteria acclimate to environment (gene regulation, production of metabolites); no significant replication

41
Q

Exponential phase

A

Bacterial growth and division at same rate; doubling time differs amongst bacteria

42
Q

Stationary phase

A

Nutrients depleted; metabolic toxins high; cell division equals cell death

43
Q

Decline phase

A

No bacterial growth; cells dying

44
Q

Requirements for bacterial growth

A

Carbon and nitrogen source, energy source, water

45
Q

Bacteria utilize different carbon sources and produce different end products, enabling…..

A

For the differentiation and identification of specific bacteria

46
Q

Fermentation

A

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
Q

MacConkey Agar

A

Tests for ability to ferment lactose

48
Q

ETC localized….

A

To plasma membrane of bacterial cells

49
Q

How does the ETC differ from mitochondrial ETC?

A
  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
Q

Tools used to differentiate and identify bacteria

A

Oxidase test and nitrate reduction test

51
Q

Obligate aerobe

A

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
Q

Microaerophile

A

Requires certain percentage of oxygen

53
Q

Aerotolerant anaerobe

A

Oxygen doesn’t matter

54
Q

Facultative anaerobe

A

Prefers oxygen but can grow without; enzymes to negate ROS present

55
Q

Obligate anaerobe

A

Oxygen is toxic; does not contain enzymes to negate ROS

56
Q

Iron acquisition

A

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
Q

Capnophile

A

High CO2

58
Q

Halophile

A

High salt

59
Q

Mesophile

A

Optimal growth at 20-45 celcius

60
Q

Obligate intracellular bacteria

A

Replicate inside host cells

61
Q

Facultative intracellular bacteria

A

Prefer to replicate inside host cells but can replicate outside host cells

62
Q

Extracellular bacteria

A

Replicate outside host cells

63
Q

Pathogen

A

Organism that causes disease

64
Q

Opportunistic pathogen

A

Organism that causes disease in immunocompromised individuals

65
Q

Infectious disease

A

Disease caused by an organism

66
Q

Virulence

A

Ability of an organism to cause disease

67
Q

Virulence factor

A

Trait that enhances disease by helping survival of bacteria

68
Q

Contagious disease

A

Transmissibility of disease from individual to individual

69
Q

Virulence factors/mechanisms

A

Antigenic variation, adhesins, biofilm, chemotaxis, capsule, lipases, motility, nucleases, proteases, siderophores, and toxins

70
Q

Pathogenesis

A
  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
Q

Toxins of pathogenesis

A
  1. ) Endotoxin (LPS) - glycolipid that elicits robust immune response
  2. ) Exotoxin - protein that is released from bacteria cell
72
Q

Intoxication

A

A toxin is directly causing the disease

73
Q

Infection

A

The pathogen is causing the disease

74
Q

Pathogenesis immune evasions

A
  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
Q

Phagocytosis evasion methods

A 
Resist ROS
Prevent phagosome from fusing to lysosome
Escape from phagosome
Prevent phagocytosis
Kill phagocytes

Foundations Exam 2 (8 decks)

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