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Microbiology > Bacterial Morphology and Growth > Flashcards

Bacterial Morphology and Growth Flashcards

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Biology 101 flashcards
1
Q

Which is more tightly coiled and flexible, spirochete or spirillum?

A

spirochete

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2
Q

A bacterium with no defined shape, or a shape that changes with the environment is called

A

pleomorphic

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3
Q

Strepto =

A

chain

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4
Q

staphylo =

A

cluster

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5
Q

sarcina =

A

packet of 8 cells

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6
Q

Do most bacterial cell membranes contain sterols?

A

no

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7
Q

Are the below functions of bacterial cell membrane or bacterial cell wall?

Maintenance of cell shape

Prevention of osmotic lysis

Environmental protection

Anchor for external structures

A

cell wall

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8
Q

This is a disaccharide chain (NAG-NAM) cross-linked by tetrapeptides common in virtually all cell walls…

A

peptidoglycan

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9
Q

Lysozyme, found in egg whites, tears and secretions, and in granules of granulocytes (PMNs), can disrupt what bacterial structure?

A

peptidoglycan

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10
Q

What is the process by which lysozyme acts against peptidoglycan?

A

weakens integrity of the cell wall even in non-growing bacteria

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11
Q

in order for synthesized antimicrobials to be effective against peptidoglycan, the bacteria must be…

A

growing

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12
Q

Gram negative, or positive:

Thin peptidoglycan layer

A

G-

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13
Q

Gram negative or positive:

Thick peptidoglycan layer

A

G+

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14
Q

A gram stain utilized what number of stains in order to determine peptidoglycan thickness?

A

two stain

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15
Q

what is the protocol for a Gram stain?

A
  1. add crystal violet
  2. add grams iodine
  3. add alcohol or acetone to decolorize
  4. add safranin red
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16
Q

G+ stains the color ________ because_______

A

purple

because crystal violet and iodine can’t escape peptidoglycan during decolorization

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17
Q

G- stains the color _______ because _______.

A

Red

because the think peptidoglycan layer allows crystal violet to be washed out with decolorizer

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18
Q

The following are G+ or G-?

Actinomyces israelii

Corynebacterium diptheriae

Staph aureus

A

G+

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19
Q

The following are G+ or G?

E. coli

H. flu

N. gonorrhoeae

A

G-

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20
Q

An initial gram stain is important because it tells the clinician what two things?

A
  1. which additional tests to perform to make definitive ID

2. what empiric abx to use

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21
Q

What are the three main types of cell walls found in bacteria?

A

G+

G-

Acid-fast

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22
Q

This type of cell wall has the following characteristics:

  1. LPS, Trimeric Proteins, Lipoprotein in OUTER MEMBRANE
  2. Has periplasmic space
  3. 1-2 layer thick peptidoglycan
A

G-

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23
Q

The outermost layer of G- cell walls is composed of…

A

lipopolysaccharide (LPS)

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24
Q

The O antigen is located where?

A

the outer portion of LPS

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25
Q

This structure of G- cell walls has the following characteristics:

long, linear CHO units

Species and strain specific

attachment site which inhibits phagocytosis

Variable and immunogenic, used to identify G- strains

A

O antigen

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26
Q

This structure of G- cell walls has the following characteristics:

Endotoxin

Responsible for bacterial sepsis

heat stable

B cell mitogen

Induces cytokine/inflammatory mediator production

A

Lipid A

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27
Q

This structure of G- cell walls has the following characteristics:

non-specific, trimeric channel

allows water and small molecules across outer membrane

A

porins

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28
Q

This structure of G- cell walls has the following characteristics:

Most abundant protein of G- cells

Stabilizes outer membrane

Anchors outer membrane to peptidoglycan layer

A

lipoprotein

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29
Q

This is the space between the outer membrane and cell membrane

it houses a thin peptidoglycan layer, transport proteins and hydrolytic enzymes

A

Periplasmic space

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30
Q

The below are common genera of what type of bacteria?

Escherichia
Salmonella
Neisseria
Pseudomonas

A

G-

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31
Q

These two structures are part of G+ cell walls and provide elasticity and stability…

A

wall teichoic acids

lipoteichoic acids

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32
Q

Wall teichoic acids are anchored to…

A

peptidoglycan

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33
Q

lipoteichoic acids are anchored to…

A

cell membrane

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34
Q

The two main functions of WTA and LTA that confer virulence to G+ organisms:

A

fxn as adhesins which stick to host cells to intiate invasion

initiate endotoxin activity when released

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35
Q

The following genera are considered G+ or G-?

Staphylococcus

Streptococcus

Bacillus

Lactobacillus

Listeria

A

G+

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36
Q

The following genera are considered G+ or G-?

Staphylococcus

Streptococcus

Bacillus

Lactobacillus

Listeria

A

G+

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37
Q

This type of bacterial cell wall structure has the following characteristics:

FA polymer covalently linked to peptidoglycan via arabinogalactan

Gives organism a “waxy coat” which resists dessication, abx, and inhibits phagocytosis

Contains tetrameric porins

A

Mycolic acid layer of Acid Fast organisms

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38
Q

the presence of ______ renders acid fast organisms unable to stain in a Gram stain

A

mycolic acid

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39
Q

In acid-fast staining, _______ is the primary stain and ________ is the counterstain

A

primary: carbol fuchsin

Counterstain: methylene blue

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40
Q

The following organisms are what type?

Nocardia

Mycobacterium

A

acid fast

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41
Q

What are the three major components of the flagellum?

A

Filament

Hook

Basal Body

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42
Q

This external bacterial structure contains:

an H antigen

self-assembling helican arrangement of flagellin protein subunits

has a hollow core

A

filament

43
Q

This external bacterial structure:

attaches filament to the cell

links to the basal body

A

Hook

44
Q

This external bacterial structure:

anchors the flagellum in the cell wall and cell membrane

A

basal body

45
Q

This bacterial external structure:

G+ and G-

forms capsules or slime layer

confers protection and prevents attachment

Source of K antigen

A

Glycocalyx

46
Q

These proteinaceous structures have adhesins on the tips.

A

pili

47
Q

This external bacterial structure:

is composed of pilin subunits

tip contains lectin adhesins which bind to sugars

have role in adhesion and twitch motility

A

common pili, fimbriae

48
Q

This external bacterial structure:

some G- bacteria

allow exchange of DNA between adhered bacteria

confers abx resistance

A

sex pili, conjugation pili

49
Q

Do bacterial DNA have introns or histones?

A

no

50
Q

Bacterial ribosomes are different from eukaryotes in that they are ______S, with ______ and ______ subunits

A

70S

30S and 50S subunits

51
Q

This internal bacterial structure:

function as storage depots

A

inclusion bodies

52
Q

these inclusion bodies are polymers of inorganic phosphate…

A

volutin granules

53
Q

these inclusion bodies are polymers of alpha-D-glucose

A

glycogen granules

54
Q

these inclusion bodies are chains of beta-hydroxybutyric acid

A

PHB granules

55
Q

What triggers endospore formation?

A

nutrient depletion

56
Q

Endospores contain what 5 things?

A
  1. one chromosome
  2. low amounts of ribosomes/essential proteins
  3. peptidoglycan layer
  4. high concentration of calcium bound to dipicolinic acid
  5. keratin coat
57
Q

Are endospores a form of reproduction?

A

no

58
Q

For how long can endospores persist in the environment?

A

months to years

59
Q

Calcium dipicolinate in endospores confers increased resistance to what?

A

heat

60
Q

The endospore’s keratin coat renders the endospore impervious to what?

A

chemicls

61
Q

What are two clinically relevant G+ endospore forming genera?

A

bacillus and clostridium

62
Q

Bacillus cereus have a _______ endospore while bacillus subtilis have a _________.

A

cereus: central
subtilis: subterminal

63
Q

What feature of endospores in bacteria aid with identification?

A

location inside the cell

64
Q

What three tests measure bacterial growth?

A

optical density

colony-forming unit

biomass

65
Q

which method of measuring bacterial growth measures viable cells only?

A

CFU

66
Q

Which phase of the bacterial growth curve has the following characteristics?

  • no cell division
  • increase in biomass
A

lag phase

67
Q

why does biomass increase during the lag phase?

A

biosynthesis of macromolecules

68
Q

the length of time a bacteria spends in the lag phase is dependent on what?

A

form and availability of nutrients

condition of the bacteria/inoculum

69
Q

Which phase of the bacterial growth curve has the following characteristics?

  • exponential growth and division
  • doubling generation time
  • primary metabolite production
  • production of virulence factors
A

log phase

70
Q

Which phase of the bacterial growth curve has the following characteristics?

-production of secondary metabolites like abx and pigments

A

late log phase

71
Q

Which phase of the bacterial growth curve has the following characteristics?

  • no change in CFU, OD, Biomass
  • supplies of energy and nutrients exhausted
  • peptides and nucleic acids from dead cell renew resources
  • no population growth
A

stationary phase

72
Q

Which phase of the bacterial growth curve has the following characteristics?

  • measured only by CFU
  • negative population growth
  • insufficient resources for growth
  • exponential cell death
A

death phase

73
Q

Which broad classification of media has the following characteristics?

  • known quantities of components
  • defined C, N sources
  • eliminates variability in experiments
  • narrower growth range
  • expensive
A

Defined media

74
Q

Which broad classification of media has the following characteristics?

  • no exact formula
  • some non-chemically defined components
  • broad range of growth
  • less expensive
A

complex/undefined media

75
Q

This media is used for growing fastidious organisms. It is complex and contains growth factors…

A

enriched media

76
Q

this media selects against unwanted organisms by using a component that prevents growth of selected organisms.

A

selective media

77
Q

this media contains components that result in a visible change on the media. It does not select for specific organisms, but can help identify between organisms…

A

differential media

78
Q

What type of media is a MacConkey agar

A

differential and selective

79
Q

MacConkey agar is differential for what characteristic?

A

lactase +/-

80
Q

MacConkey agar is selective for what?

A

G- organisms

81
Q

What two components are added to a MacConkey agar that select for G- organisms?

A

bile salts and crystal violet

82
Q

What causes the color change in a MacConkey agar that renders this media differential?

A

pH indicator

83
Q

A pink MacConkey agar indicates…

A

Lac+ organism

84
Q

an organism that is high maintenance, requiring complex diet is known as…

A

fastidious

85
Q

fastidious organisms are difficult to grow where?

A

in vitro

86
Q

what media is required in order to grow fastidious organisms?

A

enriched media

87
Q

Haemophilus and Neisseria are fastidious organisms that require what for growth?

A

hemin and NAD

88
Q

On what media will Haemophilus and Neisseria grow?

A

chocolate agar

89
Q

Chocolate agar is an enriched medium composed of…

A

lysed RBCs

90
Q

Most pathogenic bacteria can be classified as ______ because their optimum temperature is physiologic…

A

mesophiles

91
Q

What happens to bacteria at low temperature?

A

loss of enzyme activity

decreased membrane fluidity

92
Q

What happens to bacteria at high temperature?

A

denaturing of enzymes and proteins

93
Q

Diagnostic media for human pathogens has a pH of ____, classifying these pathogens as_______

A

pH 7.0

neutrophiles

94
Q

bacillus and vibrio genera are what class, in reference to pH?

A

alkaphiles

95
Q

lactobacillus, coxiella genera are what class, in reference to pH

A

acidophiles

96
Q

Regarding O2…This group:

  • requires oxygen
  • has enzymes for ROS
A

obligate aerobes

97
Q

Regarding O2…This group:

  • uses oxygen if available, but not required for survival
  • has enzymes for ROS
A

Facultative aerobe/anaerobe

98
Q

Regarding O2…This group:

  • O2 is toxic
  • Doesn’t have ROS enzymes
A

obligate anaerobe

99
Q

What enzymes reduce ROS to H2O?

A

superoxide dismutase

catalase

peroxidase

100
Q

What pathogens are capnophilic?

A

neisseria

haemophilus

helicobacter

capnocytophaga

101
Q

How do you grow capnophiles?

A

candal jar housing

CO2 packed or incubator

automated systems

102
Q

Mycobacterium resist dessication via…

A

cell wall modification

103
Q

bacillus and clostridium resist dessication via…

A

spore formation

104
Q

Osmophiles require what for growth?

A

high osmolarity/sugar

Microbiology (13 decks)

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