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PID BLOCK3- bacteriology Flashcards

1
Q

Ribosomes

A
  • ribonucleoproteins w large 50s and small 30s subunit
  • protein synthesis + translation

-target for antibiotics

  • 16s rRNA gene encoding for 30s subunit used for reconstructing phylogenies
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2
Q

Plasma membrane

A

inner membrane next to cytoplasm
-PHOSPHOLIPID BILAYER + PROTEINS

-where energy is stored

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3
Q

Proteins in the plasma membrane

A
  1. Transport proteins
  2. Energy generation components
  3. Proteins that anchor or help assemble
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4
Q

Transport proteins

A
  • in the plasma membrane

-transport of specific molecules in and out of cell

  • mediates passage of hydrophilic substances
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5
Q

Energy generating components

A

synthesis of ATP in plasma membrane

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6
Q

Phospholipid bilayer

A

Part of plasma membrane

-hydrophobic/hydrophilic sides

-Hydrophobic/ lipid solube can pass with passive diffusion

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7
Q

Main functions of plasma membrane

A
  1. Selective permeability barrier
  2. Bacterial respiration and energy generation
  3. Anchor for external structures
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8
Q

Cell wall

A

PEPTIDOGLYCAN LAYER

-mesh like structure containing alternating subunits of NAG and NAM cross-linked w peptides by transpeptidase enzymes called Penicillin binding proteins (PBPs)

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9
Q

Peptidoglycan

A

Bacteria cell wall, good target for antibiotics

polymer unique to prokaryotic cells

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10
Q

Penicillin- binding proteins

A

PBPs

  • transpeptidase enzymes that connect with NAG and NAMs in cell wall
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11
Q

Function of cell wall

A
  1. Protection against mechanical damage and osmotic lysis
  2. Transport: non selective permeability
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12
Q

Outer membrane

A
  • Only in Gram neg bacteria

Protein containing asymmetrical lipid bilayer (LIPOPOLYSACCHARIDE or endotoxin)

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13
Q

Function of outer membrane

A

Only in gram neg

  1. Selective permeability
  2. Resistance to large or hydrophobic toxic compounds
  3. Tolerance to detergents + bile salts
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14
Q

Lipopolysaccharides

A
  • in the outer membrane of gram neg bacteria

-virulence factor

lipid A component = endotoxic activity

Mediator of septic shock

heat stable

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15
Q

Symptoms of LPS

A
  • Fever
  • Leukopenia
  • Anorexia
  • Diarrhea
  • Blood coag
  • Hemorrhagic shock
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16
Q

The exceptions to the 2 main structural classes of bacteria are?

A

Mycobacteria and Mollicutes (mycoplasma)

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17
Q

Mycobacteria

A

Bacterial envelope is gram + but contains MYCOLIC ACID

-Acid fast staining for identifying

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18
Q

Mollicutes (Mycoplasma)

A

Plasma membrane w sterols

NO CELL WALL- no peptidoglycan layer

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19
Q

Capsule

A

POLYSACCHARIDE LAYER

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20
Q

Function of the capsule

A
  1. Protection
  2. Virulence factors
  3. Nutrient reserve
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21
Q

Endospores

A
  • Cryptobiotic state of dormancy, most durable

-Produced by Bacillus and Clostridium

-keratin spore coat helps survival

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22
Q

Function of endospores

A
  1. Ensure survival during adverse enviro conditions
  2. Dormant, highly resistant bodies
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23
Q

Flagella

A

-on bacterial surface

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24
Q

Flagella function

A

locomotion or bacterial motility

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25
Pili/Fimbriae
- Fine, straight hair-like, attached to cell wall - Most common on Gram neg bacteria for adhesion
26
Function of pili/Fimbriae
1. Adhesion to host tissues 2. Contribute to antigenicity
27
Bacterial colony
single bacterium multiplies on solid growth media. Growth of bacteria produces a colony that is visible without microscope
28
Different morphology depends on
Culture medium Incubation time Temp Oxygen Genetic differences
29
Environmental factors of bacterial growth
1. Nutrients 2. pH (best growth @ 7.2-7.4) 3. Ionic strength + osmotic pressure 4. Light 5. Temp (most are mesophilic w growth at 30-37 C) 6. Gaseous requirement: O2 or CO2
30
Classification of bacteria based on O2
1. Obligate aerobes 2. Obligate anaerobes 3. Facultative anaerobes 4. Aerotolent anaerobes
31
Generation time
time required for a single bacterial cell to yield 2 daughter cells (30 min- 20 hrs)
32
How do bacteria replicate?
Binary fission
33
Bacterial growth curve
1. Lag phase 2. Exponential phase/ logarithmic phase 3. Maximal stationary phase 4. Decline phase/ death phase
34
Lag phase
cell size increases active metabolism but no division
35
Exponential or Logarithmic phase
cells multiply at maximum rate
36
Maximal stationary phase
Due to exhaustion of nutrients or toxic byproducts Growth is ceased
37
Fungal characteristics
1. Eukaryotic 2. Non-photosynthetic heterotrophs 3. Aerobic growth Cell membrane contains sterols (ergosterol) and chitin
38
Mycelium
filamentous mass of hyphae
39
Convalescent carrier
recovered but continues to shed pathogen Ex: strangles in horses
40
Incubatory carrier
incubating pathogen but not yet ill shedding of pathogen during incubation period
41
Strangles in horses
- detection of convalescent carriers - contagious febrile disease of URT w abscess of lymph nodes
42
Pathogenicity islands
carry genes coding 1 or more virulence factors - horizontal gene transfer - mobile, located on bacterial chromosome or plasmids
43
Quorum sensing
regulates gene expression in response to changes in cell density Mediated by chemical signal molecules (autoinducers) Low density= individual cell behavior High density= group behavior makes biofilm
44
Virulence factors that play a role in adherence
1. Flagella 2. Pili/ Fimbriae 3. Capsule= glycocalyx.. layer of exopolysaccharides
45
Invasion
ability of pathogen to spread to other locations in host by invading host cells/tissues
46
Extracellular invasion
breaks down barriers of tissue to disseminate in host while remaining outside host cell Production of extracellular enzymes
47
Intracellular invasion
bacteria penetrates cell and survives within enviro - Facultative intracellular - Obligate intracellular
48
Exotoxins
Proteinaceous toxins Delivery by: 1. Secretion into milieu 2. Direct injection into host cell
49
Type 1 Exotoxin
1. Active @ cell surface 2. Disturbs cell metabolism by binding to receptors on cell surface Ex: clostridium perfringens
50
Type 2 Exotoxin
damages membranes of cells Ex: staph aureus
51
Type 3 Exotoxin
Intracellar, needs transport protein to be brought in (A-B toxins) Ex: clostridium botulinum
52
Types of proteolytic toxins?
1. Botulinum toxin 2. Tetanus toxin
53
Endotoxins
component of prokaryotic cell wall, not released until cell death and lysis of bacteria Effect: fever, diarrhea, weakness, blood coag, septic shock, death
54
(Lipo) Teichoic Acid
Only in GRAM + Mediator of septic shock
55
Does exotoxins have low or high toxicity?
High toxicity
56
Do endotoxins have low or high toxicity?
Low toxicity
57
Where is the gene location for exotoxins vs endotoxins?
Exotoxins= on plasmids Endotoxins= on bacterial chromosome
58
Heat stability for exotoxin vs endotoxin?
Exotoxin= heat labile Endotoxin= heat stable
59
Are vaccines available for exotoxins or endotoxins?
Only available for exotoxins (toxoids)
60
Antigenicity of exotoxin vs endotoxin
Exotoxin= highly antigenic Endotoxin= poorly antigenic
61
What species are exotoxins found in?
Both gram positive and gram negative
62
What species are endotoxins found in?
Mostly gram neg and Listeria
63
True or false: Endotoxins are part of the cell wall
TRUE
64
What is the protein location of exotoxins?
Proteins secreted from cell
65
Biofilms
Mass of bacteria, clings to surfaces Produces extracellular polymer matris and exchanges nutrients
66
Functions of biofilms
1. Bacterial persistence (endocarditis) 2. Reduc. of host immunity 3. Local damage (Ex: catheters) 4. Reduced susceptibility to antibiotics
67
Iron uptake
needed for bacterial growth Bacterial cytotoxins damage host by releasing ferritin, hemoglobin, lactoferrin Receptor mediated recognition

PID (13 decks)

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