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HDID 2 > 29. Bacterial Structure and Characteristics > Flashcards

29. Bacterial Structure and Characteristics Flashcards

1
Q

archaea vs bacteria

A

archaea: ancient, single cell, cell wall differences to bacteria, LACK PEPTIDOGLYCAN, no human pathogens
bacteria: NO NUCLEAR MEMBRANE, distinct biochem and RNA markers, asymmetrical membrane

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2
Q

structural components (fimbriae, capsule, flagellum), cell wall (gram + or -), and genetic makeup are three general ways to ____ bacteria

A

classify

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3
Q

obligate aerobes _____ oxygen

A

require

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4
Q

microaerophiles ______ oxygen

A

require reduced

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5
Q

obligate anaerobes _____ oxygen

A

require no

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6
Q

facultative anaerobes ____ oxygen

A

they are anaerobic or aerobic

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7
Q

capnophiles _____ oxygen

A

require INCREASED CO2

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8
Q

what are 6 general levels we use to classify bacteria?

A
  1. shape
  2. gram reaction
  3. atmosphere
  4. spores
  5. biochemisty/genetic classification
  6. serology typing
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9
Q

what shape to staphylococci make?

A

like grapes

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10
Q

what shape to vibrio make?

A

like a comma

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11
Q

what shape do Bdellovibrio make?

A

comma with a tail

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12
Q

what shape do borrelia burgdorgeri make?

A

corkscrew

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13
Q

what shape does syphilis make?

A

spirochete

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14
Q

what shape does helicobacter pylori make?

A

helical

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15
Q

what shape are palisades?

A

bacili lined up in columns

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16
Q

are cocci normally gram - or +?

A

+

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17
Q

are bacilli normally gram - or +?

A

-

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18
Q

what is a red blood plate vs a chocolate blood plate?

A

RBCs intact in red, RBCs popped in chocolate (see iron)

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19
Q

what do alpha bacteria do on a red blood plate?

A

start to get conversion of hemoglobin to methemoglobin so turns brown

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20
Q

what do beta bacteria do on a red blood plate?

A

complete hemolysis - no RBCs around bacteria

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21
Q

what do gamma bacteria do on a red blood plate?

A

nothing

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22
Q

what 4 structures are common to all bacteria?

A

cell membrane/envelope

cytoplasm

ribosomes

one (or a few) chromosomes (eg E. coli technically has one but the chromosomes replicate at a different rate than the cell can divide so often find multiple in one cell)

23
Q

layer number for each:

gram +
Gram -
acid fast

A

gram + (2 layers)

  • cell wall (peptidoglycan)
  • cytoplasmic membrane

gram - (3 layers)

  • cytoplasmic membrane
  • cell wall
  • outer membrane

acid fast bacteria (2.5 layers)

  • cytoplasmic membrane
  • cell wall
  • acyl layer
24
Q

gram + cell wall structure?

A
  • thick peptidoglycan cell wall (40+ layers)
  • resists lysis by complement
  • teichoic acids and lipoteichoic (LTA) polymers
  • other proteins and carbs (enzymes/adhesions)
  • TLR2 recogntion (LTA)
  • inner membrane has 2 leaflets and is symmetrical, outer is NOT
25
Q

gram - cell wall structure?

A
  • asymmetric outer membrane (outer leaflet composed of LPS, inner leaflet of peptidoglycans)
  • thin peptidoglycan layer
  • periplasmic space b/w membrane (aqueous)
  • barrier to non-polar molecs
  • outer membrane porins (nable diffusion across outer membrane, barrier to large polar molecs)
  • TLR4 recognition (LPS)
26
Q

acid fast cell envelope?

A
  • most similar to gram-positive cells (mycobacteria…so hard to treat thanks to the novel molecules in its membrane)
  • cell wall comprised of fatty acids and waxes
  • lipid components difficult to stain but once stained, stay stained
  • mycolic acid, WAX D (much more rigid), arabinogalactans and sulfolipids present in cell wall
  • TLR1/2/6 recognition
27
Q

steps to gram stain?

A

fixation - crystal violet - iodine treatment (crosslinks peptidoglycan to change it from porous to tight closed so that gram+ retains violet) - decolorization - counter stain safranin (red)

28
Q

what pathogens have acid fast cell wall?

A

mycobacterium

29
Q

acid fast staining procedure?

A
  • stain with carbolfuchsin
  • resists decolorization with acid alcohol
  • counter stain with methylene blue
30
Q

peptidoclygan cell wall is unique to what?

A

prokaryotes

31
Q

the peptidoglycan is what?

A

polymer consisting of 2 sugars and 5 aa’s that forms a mesh-like layer outside of the cytoplasmic membrane

  • gives strong structural support (gram + thick, 90% dry weight; gram - thin, 10% dry weight)
  • rigid (protects vs osmotic pressures)
  • involved in bacterial replicatoin
  • TARGET OF MANY ANTIBIOTICS
32
Q

sugars of the peptidoglycan prokaryotic cell wall?

A

NAG and NAM (alternating)

they make up the backbone and they are cross linked by peptides and there are tetrapeptide cross chains to keep Nag and Nam together

33
Q

gram + amino acids of NAM/NAG peptidoglycan monomer?

A 
L-alanine
D-glutamine
L-lysine
D-alanine
D-alanine
34
Q

gram - amino acids of NAM/NAG peptidoglycan monomer?

A 
L- alanine
D- glutamic acid
meso diaminopimelic acid
D-alanine
D-alanine
35
Q

what makes the aa’s pentapeptide of the prokaryotic peptidoglycan unique?

A

has D-forms of aa’s that do not occur in human proteins and are thought to help vs attack by peptidases

36
Q

enzymes required for peptidoglycan synthesis?

A

transglycosylase (inserts and links new peptidoglycan monomers)

transpeptidase (forms the peptide cross-links between the rows and layers of peptidoglycan) *** common target to keep bacteria from replicating

37
Q

bacterial motility with flagella - forward vs backward motion

A

anticlockwise rotation: forward movement, swimming (chemoattractant)

clockwise rotation: tumbling movement, reorientation

38
Q

flagella are present on which types of bacteria?

A

bacilli and spirochetes, but not cocci (so don’t see on gram +, ie never see staph and strep w/flagella)

39
Q

3 parts of flagella?

A

filament, hook (sheath), and basal body

40
Q

what is a single flagella called- what is an example?

A

monotrichous (vibrio)

41
Q

what are multiple flagella from one spot called?

A

lophotrichous

42
Q

what are one flagella from each end called?

A

amphitrichous

43
Q

what are many flagella in multiple directions called - what is an exam?

A

peritrichous (E.coli)

44
Q

pili/fimbriae are present on gram+ or gram- bacteria?

A

both

45
Q

what motility is afforded thanks to fimbriae?

A

twitching motility - grappling hook (type IV)

gives adhesion to surface and each other

46
Q

fimbriated strains of E.coli can do what to RBCs?

A

agglutinate

47
Q

how are pili used in bacterial sex?

A

exchange of genetic material = CONJUGATION

48
Q

are fimbriae or pili longer?

A

pili

49
Q

do gram+ or gam- bacteria have glycocalyx?

A

both

50
Q

what is the purpose of the glycocalyx?

A

helps the cell adhere ot the env’t (biofilm) or is a virulence factor

and protects bacteria from phagocytes - keeps macrophages at arm’s length, looks like host, and really big for macrophages to engulf

51
Q

slime layer vs capsule glycocalyx?

A

slime layer: loosely assoc with the cell
- protects from dehydration and loss of nutrients

capsule: firmly attached to cell wall (so doesn’t slough off)
- gummy, sticky consistency
- protects similar to slime layer
- adhesion to surfaces and nutrients

52
Q

endospores are found in gram+ or - bacteria?

A

certain gram+ (bacillus and clostridium)

53
Q

what is the endospore?

A

a dormant, tough, and temporarily non-reproductive structure

  • resistant to extreme heat/radiation but can be destroyed by autoclave or burning
  • mult layers
  • when env’t returns favorable,it can germinate itself

some have crystals of nutrients too

54
Q

classes of plasmids?

A

fertility plasmids - conjugation

resistance plasmids - resistance vs antibiotics

col plasmids - contain genes that code bacteriocins that kill other bacteria

degradative plasmids - digestion of unusual substances

virulence plasmids - turn bacterium into a pathogen

HDID 2 (32 decks)

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