Bacterial Morphology and Growth Flashcards
1
Q
Which is more tightly coiled and flexible, spirochete or spirillum?
A
spirochete
2
Q
A bacterium with no defined shape, or a shape that changes with the environment is called
A
pleomorphic
3
Q
Strepto =
A
chain
4
Q
staphylo =
A
cluster
5
Q
sarcina =
A
packet of 8 cells
6
Q
Do most bacterial cell membranes contain sterols?
A
no
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
8
Q
This is a disaccharide chain (NAG-NAM) cross-linked by tetrapeptides common in virtually all cell walls…
A
peptidoglycan
9
Q
Lysozyme, found in egg whites, tears and secretions, and in granules of granulocytes (PMNs), can disrupt what bacterial structure?
A
peptidoglycan
10
Q
What is the process by which lysozyme acts against peptidoglycan?
A
weakens integrity of the cell wall even in non-growing bacteria
11
Q
in order for synthesized antimicrobials to be effective against peptidoglycan, the bacteria must be…
A
growing
12
Q
Gram negative, or positive:
Thin peptidoglycan layer
A
G-
13
Q
Gram negative or positive:
Thick peptidoglycan layer
A
G+
14
Q
A gram stain utilized what number of stains in order to determine peptidoglycan thickness?
A
two stain
15
Q
what is the protocol for a Gram stain?
A
- add crystal violet
- add grams iodine
- add alcohol or acetone to decolorize
- add safranin red
16
Q
G+ stains the color ________ because_______
A
purple
because crystal violet and iodine can’t escape peptidoglycan during decolorization
17
Q
G- stains the color _______ because _______.
A
Red
because the think peptidoglycan layer allows crystal violet to be washed out with decolorizer
18
Q
The following are G+ or G-?
Actinomyces israelii
Corynebacterium diptheriae
Staph aureus
A
G+
19
Q
The following are G+ or G?
E. coli
H. flu
N. gonorrhoeae
A
G-
20
Q
An initial gram stain is important because it tells the clinician what two things?
A
- which additional tests to perform to make definitive ID
2. what empiric abx to use
21
Q
What are the three main types of cell walls found in bacteria?
A
G+
G-
Acid-fast
22
Q
This type of cell wall has the following characteristics:
- LPS, Trimeric Proteins, Lipoprotein in OUTER MEMBRANE
- Has periplasmic space
- 1-2 layer thick peptidoglycan
A
G-
23
Q
The outermost layer of G- cell walls is composed of…
A
lipopolysaccharide (LPS)
24
Q
The O antigen is located where?
A
the outer portion of LPS
25
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
O antigen
26
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
Lipid A
27
This structure of G- cell walls has the following characteristics:
non-specific, trimeric channel
allows water and small molecules across outer membrane
porins
28
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
lipoprotein
29
This is the space between the outer membrane and cell membrane
it houses a thin peptidoglycan layer, transport proteins and hydrolytic enzymes
Periplasmic space
30
The below are common genera of what type of bacteria?
Escherichia
Salmonella
Neisseria
Pseudomonas
G-
31
These two structures are part of G+ cell walls and provide elasticity and stability...
wall teichoic acids
lipoteichoic acids
32
Wall teichoic acids are anchored to...
peptidoglycan
33
lipoteichoic acids are anchored to...
cell membrane
34
The two main functions of WTA and LTA that confer virulence to G+ organisms:
fxn as adhesins which stick to host cells to intiate invasion
initiate endotoxin activity when released
35
The following genera are considered G+ or G-?
Staphylococcus
Streptococcus
Bacillus
Lactobacillus
Listeria
G+
36
The following genera are considered G+ or G-?
Staphylococcus
Streptococcus
Bacillus
Lactobacillus
Listeria
G+
37
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
Mycolic acid layer of Acid Fast organisms
38
the presence of ______ renders acid fast organisms unable to stain in a Gram stain
mycolic acid
39
In acid-fast staining, _______ is the primary stain and ________ is the counterstain
primary: carbol fuchsin
Counterstain: methylene blue
40
The following organisms are what type?
Nocardia
Mycobacterium
acid fast
41
What are the three major components of the flagellum?
Filament
Hook
Basal Body
42
This external bacterial structure contains:
an H antigen
self-assembling helican arrangement of flagellin protein subunits
has a hollow core
filament
43
This external bacterial structure:
attaches filament to the cell
links to the basal body
Hook
44
This external bacterial structure:
anchors the flagellum in the cell wall and cell membrane
basal body
45
This bacterial external structure:
G+ and G-
forms capsules or slime layer
confers protection and prevents attachment
Source of K antigen
Glycocalyx
46
These proteinaceous structures have adhesins on the tips.
pili
47
This external bacterial structure:
is composed of pilin subunits
tip contains lectin adhesins which bind to sugars
have role in adhesion and twitch motility
common pili, fimbriae
48
This external bacterial structure:
some G- bacteria
allow exchange of DNA between adhered bacteria
confers abx resistance
sex pili, conjugation pili
49
Do bacterial DNA have introns or histones?
no
50
Bacterial ribosomes are different from eukaryotes in that they are ______S, with ______ and ______ subunits
70S
30S and 50S subunits
51
This internal bacterial structure:
function as storage depots
inclusion bodies
52
these inclusion bodies are polymers of inorganic phosphate...
volutin granules
53
these inclusion bodies are polymers of alpha-D-glucose
glycogen granules
54
these inclusion bodies are chains of beta-hydroxybutyric acid
PHB granules
55
What triggers endospore formation?
nutrient depletion
56
Endospores contain what 5 things?
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
Are endospores a form of reproduction?
no
58
For how long can endospores persist in the environment?
months to years
59
Calcium dipicolinate in endospores confers increased resistance to what?
heat
60
The endospore's keratin coat renders the endospore impervious to what?
chemicls
61
What are two clinically relevant G+ endospore forming genera?
bacillus and clostridium
62
Bacillus cereus have a _______ endospore while bacillus subtilis have a _________.
cereus: central
subtilis: subterminal
63
What feature of endospores in bacteria aid with identification?
location inside the cell
64
What three tests measure bacterial growth?
optical density
colony-forming unit
biomass
65
which method of measuring bacterial growth measures viable cells only?
CFU
66
Which phase of the bacterial growth curve has the following characteristics?
- no cell division
- increase in biomass
lag phase
67
why does biomass increase during the lag phase?
biosynthesis of macromolecules
68
the length of time a bacteria spends in the lag phase is dependent on what?
form and availability of nutrients
condition of the bacteria/inoculum
69
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
log phase
70
Which phase of the bacterial growth curve has the following characteristics?
-production of secondary metabolites like abx and pigments
late log phase
71
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
stationary phase
72
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
death phase
73
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
Defined media
74
Which broad classification of media has the following characteristics?
- no exact formula
- some non-chemically defined components
- broad range of growth
- less expensive
complex/undefined media
75
This media is used for growing fastidious organisms. It is complex and contains growth factors...
enriched media
76
this media selects against unwanted organisms by using a component that prevents growth of selected organisms.
selective media
77
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...
differential media
78
What type of media is a MacConkey agar
differential and selective
79
MacConkey agar is differential for what characteristic?
lactase +/-
80
MacConkey agar is selective for what?
G- organisms
81
What two components are added to a MacConkey agar that select for G- organisms?
bile salts and crystal violet
82
What causes the color change in a MacConkey agar that renders this media differential?
pH indicator
83
A pink MacConkey agar indicates...
Lac+ organism
84
an organism that is high maintenance, requiring complex diet is known as...
fastidious
85
fastidious organisms are difficult to grow where?
in vitro
86
what media is required in order to grow fastidious organisms?
enriched media
87
Haemophilus and Neisseria are fastidious organisms that require what for growth?
hemin and NAD
88
On what media will Haemophilus and Neisseria grow?
chocolate agar
89
Chocolate agar is an enriched medium composed of...
lysed RBCs
90
Most pathogenic bacteria can be classified as ______ because their optimum temperature is physiologic...
mesophiles
91
What happens to bacteria at low temperature?
loss of enzyme activity
decreased membrane fluidity
92
What happens to bacteria at high temperature?
denaturing of enzymes and proteins
93
Diagnostic media for human pathogens has a pH of ____, classifying these pathogens as_______
pH 7.0
neutrophiles
94
bacillus and vibrio genera are what class, in reference to pH?
alkaphiles
95
lactobacillus, coxiella genera are what class, in reference to pH
acidophiles
96
Regarding O2...This group:
- requires oxygen
- has enzymes for ROS
obligate aerobes
97
Regarding O2...This group:
- uses oxygen if available, but not required for survival
- has enzymes for ROS
Facultative aerobe/anaerobe
98
Regarding O2...This group:
- O2 is toxic
- Doesn't have ROS enzymes
obligate anaerobe
99
What enzymes reduce ROS to H2O?
superoxide dismutase
catalase
peroxidase
100
What pathogens are capnophilic?
neisseria
haemophilus
helicobacter
capnocytophaga
101
How do you grow capnophiles?
candal jar housing
CO2 packed or incubator
automated systems
102
Mycobacterium resist dessication via...
cell wall modification
103
bacillus and clostridium resist dessication via...
spore formation
104
Osmophiles require what for growth?
high osmolarity/sugar
