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Pathogenic Microbiology > 2.1 > Flashcards

2.1 Flashcards

microbial structure: cell envelope

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1
Q

Why is microbial structure important?

A
  • virulence mechanisms: bacteria control the expression of any molecule that contributes to an organism’s virulence
  • must understand how the organism functions to understand disease
  • understand what to target on the cell to develop new medication
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2
Q

What makes up the cell envelope?

A
  1. cell membrane (inner)
  2. cell wall (middle)
  3. glycocalyx (outer)
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3
Q

What are the cell characteristics of the cell envelope?

A
  • partially responsible for structure and shape
  • toxic & immunological properties
  • some signs & symptoms
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4
Q

Functions of the cell envelope?

A

protection
- from osmotic balances
- from elimination & infection
- from chemotherapeutic drugs
metabolic
- enzymatic activities
- location of transport proteins
- origin of many signal transduction pathways
- attachments & colonization of environmental surfaces

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5
Q

shape of coccus?

A

spherical shaped

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6
Q

shape of coccobacillus?

A

spherical & rod-shaped (oval)

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7
Q

shape of bacillus?

A

rod shaped

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8
Q

shape of vibrio?

A

curved-rod shaped, comma shape

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9
Q

shape of spirilium and spirochete?

A

spiral shaped

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10
Q

diplo-?

A

two

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11
Q

tetrad?

A

four

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12
Q

sarcinae?

A

cuboidal

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13
Q

strepto?

A

chain

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14
Q

staphylo?

A

clusters

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15
Q

Which part of the cell membrane controls fluidity of bilayer similar to cholesterol?

A

hopanoid

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16
Q

What does the cell membrane do?

A

keeps things in and/or out despite chemical gradients and osmotic pressure

17
Q

What are the three important cell membrane functions?

A
  1. fast cell division
  2. proteins for response and reaction
  3. transportation of materials
18
Q

What happens during prokaryotic cell division?

A

FtsZ assembles at site of septum formation; analogous to actin ring for cytokinesis, and separates the two daughter cells and establishes cell polarity

19
Q

How are proteins involved in response and reaction?

A
  • membrane receptors initiate a response to stimuli
    ex. chemotaxis and phototaxis
  • membranes are crucial for the electron transport chain, similar to the mitochondria in eukaryotes
  • photosynthetic microbes’ cell membrane can perform photosynthesis, similar to chloroplasts in plants
    ex. purple bacteria
  • carboxysome: shell surrounding containing Rubisco for carbon fixation (photosynthesis)
20
Q

What is the endosymbiosis theory?

A

complex eukaryotes are a result of symbiotic combinations of prokaryotic cells
- mitochondria
- chloroplasts

21
Q

What is involved in the transportation of materials?

A

passive transport
- high to low
- simple diffusion
- channel-mediated
- carrier mediated
active transport
- low to high (use energy)
- ATP, light, or ion gradient

22
Q

What is a proton motive force?

A

active transport
simple transport: driven by the energy in the proton motive force
- bacteria can utilize the energy of moving protons with the gradient to transport molecules against the gradient
- similar to ATP synthase
ex. multidrug-resistant efflux pumps belong to RND family; tuberculosis

23
Q

What is group translocation?

A

active transport
chemical modification of the transport substance driven by phosphoenolpyruvate (PEP) to transport against a concentration gradient

24
Q

What are ATP-binding cassette (ABC) transporters?

A

active transport
uses energy from ATP to move a molecule
periplasmic binding proteins are involved
can use transports to move things out of the cell such as toxins and virulence factors

25
Q

what is the type I secretion system?

A

used to secrete factors such as toxins and virulence outside of the cell
- ABC transporters
ex. E. coli, vibrio cholera, and bordetella pertussis

26
Q

Functions of cell wall?

A
  • provides structure and stability for the cell
  • provides points of attachment (colonization) and receptors for viruses (bacteriophage)
  • some signs and symptoms
  • target for antibiotics/chemotherapeutic agents
  • important for classification
27
Q

Characteristics of gram-positive cell wall?

A

Stains purple
Two layers
- thick peptidoglycan (outer)
1. glycan backbone
- NAG—NAM (B-1,4 glycosidic linkage)
- 80% NAM
2. side chain (tetrapeptide chains)
- Side chain comes off NAM
- Order: L-alanine, D-glutamic, L-lysine, & D-alanine (some may have 5th D-alanine)
3. inter bridge (cross-link)
- pentaglycine inter bridge between L-lysine & D-alanine
- cell membrane (inner)

28
Q

Characteristics of a gram-negative cell wall?

A

stains pink
Three layers
- outer membrane (outer)
- thin peptidoglycan (middle)
1. glycan backbone
- NAG—NAM (B-1,4 glycosidic linkage)
- 30-40% NAM
2. side chain (tetrapeptide chains)
- side-chain comes off NAM
- Order: L-alanine, D-glutamic acid, Diaminopimelic acid, D-alanine (some may have 5th D-alanine)
3. inter bridge (cross-link)
- direct linkage between D-alanine and diaminopimelic acid
- cell membrane (inner)

29
Q

What do gram-positive microbes have in their peptidoglycan and the function?

A

teichoic acid
- structural function
- important in cell growth (has to be broken)
- important for cell adherence
- anchors cell wall into membrane

30
Q

What are bacterial porins?

A

Transport molecules through outer membrane into periplasmic space; limited selectivity

31
Q

What is unique to gram-negative microbes cell wall?

A

Lipopolysaccharide (LPS)
- Repeating O antigen
- core polysaccharide
- Lipid A embedded into bilayer, bacterial endotoxin

32
Q

What are the microbes with no repeating O antigen called?

A

Lipooligosaccharide
- Neisseria spp.
- Haemophilus spp.

33
Q

What can endotoxin toxicity lead to?

A

Sepsis
- SIRS: severe inflammatory response syndrome
- Sepsis: 2 SIRS, confirmed infection
- Severe sepsis: sepsis + signs of organ damage
- Shock: persistent signs of organ damage

34
Q

What are acid-fast cell walls?

A

mycobacteria
- named due to acid used during staining
- contains lipids
- mycolic acid (60-90 carbon chains)
ex. mycobacterium & nocardia spp.

35
Q

What are the cell “wall-less” microbes?

A

mycoplasma spp.
- m. pnuemoniae
- m. hominis
Ureaplasma spp.
- u. urealyticum

36
Q

What are microbes called when they lose their cell wall?

A

L-Forms of bacteria
- protoplasts: gram +
- spheroplasts: gram -

37
Q

What are S layer proteins?

A

repeated proteins found on the exterior of some bacterial cell walls
- increases structural integrity
- involved in attachment & protection

38
Q

What is the purpose of the glycocalyx?

A

material surrounding the cell, often a thick stick sugar coat
Two types
- slime layer: temporary & less consistent
- capsule: permanent & organized
- protection
- adherence
- biofilms connect their glycocalyx
ex. streptococcus mutans (dental plaque)
- classification
- carbohydrate reserves?

Pathogenic Microbiology (6 decks)

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