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MCB 2610 > EXAM 3: Chapter 2- Part 3 > Flashcards

EXAM 3: Chapter 2- Part 3 Flashcards

1
Q

Cell envelope

A

Plasma membrane and anything external

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2
Q

Gram Negative cell envelope

A

periplasmic space larger
periplasmic space contains peptidoglycan
also has outer membrane

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3
Q

Gram positive cell envelope

A

periplasmic space is narrower and do not find a ton of enzymes
Have teichoic and lipteichoic acids that extend into plasma membrane

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4
Q

Teichoic and lipteichoic acids

A

helps anchor the peptidoglycan into plasma membrane
contributes to net negative charge and shape

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5
Q

Where do you find LPS

A

ONLY in the outer membrane of Gram-negative

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6
Q

What is LPS composed of?

A

lipid A
core polysaccharide
O antigen

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7
Q

Lipid A

A

most internal and what anchors it to the inner leaflet of outer membrane
rigid
two fatty acid tails

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8
Q

Core polysaccharide

A

usually made up of about 10 unusual sugars

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9
Q

O antigen

A

longest and most external
may find up to 200 sugars
plays important role in evading immune response

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10
Q

How does O antigen evade immune response?

A

initial immune response recognizes sugars in O-antigen
but the bacteria can then change its sugars and go undetected

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11
Q

Why is LPS important

A

contributes negative charge on cell surface
helps stabilize outer membrane
- bcus of rigidity of Lipid A
contributes to attachment and biofilm formation
- sugar residues are sticky
creates permeability layer and protection from host defenses
can act as an endotoxin
- lipid A

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12
Q

Endotoxin

A

maintained within the cell and are not secreted

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13
Q

How does Lipid A work as an endotoxin

A

does not do anything when embedded
if lysis occurs Lipid A is released and causes a massive immune response

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14
Q

Gram-positive pores

A

peptidoglycan layer has large pores throughout its matrix
does not require much machinery

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15
Q

Gram-negative pores

A

has Porin and TonB proteins in outer membrane to transform molecules into periplasmic space
machinery for facilitated and active

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16
Q

Porin protein

A

last line of defense
more permeable than plasma membrane

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17
Q

Porin-based transport

A

Porin/channel used for facilitated diffusion in outer mem
active transport system embedded in PM

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18
Q

TonB- dependent transportant

A

active transport mechanism in the outer membrane

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19
Q

Autotransporters

A

move from the periplasm to outside environment directly
embedded part of themselves and use other part to move things across
passenger and translocator domains

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20
Q

Mechanis of Gram stain reaction- positive

A

large pores shrink
crystal violet cannot leave cell
pores seal shut when you add decolorizer

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21
Q

mechanism of Gram stain reaction- negative

A

outer membrane lipids stripped by decolorizer

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22
Q

flagella

A

spiral, hollow, rigid filaments extending from cells surface

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23
Q

monotrichous

A

one flagellum

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24
Q

polar flagellum

A

flagellum at end of cell (could be one or both)

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25
amphitrichous
one flagellum at each end
26
lophotrichous
cluster of flagella at one or both ends
27
peritrichous
flagella spread over entire surface of cell
28
Flagella are composed of 3 parts
filament hook protein basal body
29
filament
most external sits in hook protein
30
hook protein
smallest part connects the basal body to the filament
31
basal body
anchors flagella into plasma membrane
32
Gram negative flagella
Rings are connected to a central sheath L-ring in outer membrane P-ring in peptidoglycan MS-ring in plasma membrane C-ring located in cytoplasm
33
Gram positive flagella
Outer ring is peptidoglycan Inner ring is in plasma membrane
34
What is the difference between flagellar structure between Gram-stains?
basal body
35
How is flagella encoded
by operon might need up to 20 different genes to build flagella
36
operon
transcribes all genes required at the same time
37
How is flagella built?
built starting from tip Every protein is moved up through the hallow sheath and is assembled at the tip
38
Self assembly of flagella
subunits are able to organize themselves do not need outside organization
39
How do flagella rotate
like a propeller very rapidly
40
Counterclockwise rotation
causes forward motion (run) direct movement towards something
41
Clockwise roation
disrupted run causing cell to stop and tumble used to reorient themselves
42
Chemotaxis
movement toward a chemical attractant or away from a chemical repellant
43
Chemorecpetors
allow chemical attractants/ repellants to bind
44
Positive chemotaxis
Movement toward an attractant Bacteria settles at center then expands outward
45
Negative chemotaxis
Movement away from a repellant As concentration of repellant increases zone of clearance gets larger
46
In presence of attractant:
Tumbling frequency is intermittently reduced Runs in direction of attractant are longer
47
In presence of a repellant
similar to that of an attractant but opposite
48
Chemotaxis system
Default direction is counterclockwise CheW transmits signal that determines if CheY gets phosphorylated If CheY is phosphorylated it tells to change direction to clockwise
49
Mechanism for flagellar movement
2 part motor that produces torque - rotor - stator
50
rotor
C-ring (FliG protein) and MS ring turn and interat with stator Inner and outer ring in Gram-positive
51
stator
Mot A and Mot B proteins Not embedded within rings Form a channel and use energy stored in ion gradients Protons flow down gradient and down channel and release energy which powers flagella
52
How do archaea flagella move
push me-pull me alternation with no tumbles
53
What time of organisms have internal flagella
spirochetes
54
where are internal flagella located and what type of motion?
located in periplasm corkscrew-like motion
55
3 types of nonflagellar motility
gliding motility twitching motility polymerization of actin
56
Gliding motility
smooth sliding over a surface Associated with organisms that secrete a slime layer
57
twitching motility
slow jerky process using pili Extend pili and then retract it to move forward Not all organisms with pili twitch- primary function is to adhere
58
polymerization of actin
for propulsion of bacteria into adjacent cells Frequently used by intracellular bacteria Use host cell actin to polymerize it and build a tail Tail pushes the bacteria along
59
Example organism for gliding motility
Myxobacteria and cyanobacteria
60
example organism for twitching motiliity
N. meningitidis and P. aeruginosa
61
Adherence
ability to stick to surfaces mediated by pili
62
How fo pili adhere
also called fimbriae fibers of pilin protein possessother protein on their tips for sticking
63
sex pilus
different structure used for conjugation
64
Other method of adhesion
stalk
65
stalk
Use an extension of the cell envelope tipped by a “Holdfast” of polysaccharides Made my organisms in low nutrient environments - Stalk increases surface area
66
Components outside cell envelope
Glycocalyx S-layers
67
Glycocalyx
made up of polysaccharides aid in attachent to solid surfaces capsules and slime layers
68
Capsules
well organized and not easily removed from cell visible in light microscopes have protected advantages
69
What are protective advantages of capsules?
high H2O content- protection from desiccation protects organism from immune detection
70
T/F if you have capsules you are not virulent
false
71
Biofilms
Provide protection and enhanced survivability in harsh environments Composed of polysaccharides Can be single or mixed species
72
Slime layers
Usually composed of polysaccharides Held onto the cell by covalent connectionH
73
How are slime layers similar to capsules
High in water content Aid in attachment Hide from host cell immune response
74
How are slime layers different to capsules
Diffuse Are thinner Unorganized Easily removed Need EM to see
75
Example organism with slime layer
Xanthamonas campestris
76
S- layers (surface arrays)
crystalline array of interlocking proteins Found in both Gram-negative and Gram-positive Regular structured layers of protein/glycoprotein that self-assemble Highly organized and thinner
77
Where do S-layers adhere in Gram-negative
to outer membrane
78
Where do S-layers adhere in Gram-positive
associated with petidoglycan surface
79
How do S-layers adhere
via non-covalent interactions
80
T/F you can see S-layers under light microscope
TRUE but hard to visualize because it is so thin
81
Functions of S-layer
Protects from ion and pH fluctuations, osmotic stress, enzymes, and predation Maintains shape and rigidity Promotes adhesion to surfaces Protects from host defenses Potential use in nanotechnology - Because of the self-assembly of the S-layer
82
Endospore
complex, dormant (metabolically inactive) structure formed by some bacteria Clostridium and bascillus species
83
vegetative state
metabolically active non-spore forming
84
What are endospores resistant to?
Heat Radiation Chemicals Desiccation
85
Spore forming organisms are typically found where?
soil
86
What do spore formers also produce
nasty toxins
87
Endospore locations
central swollen sporangium- clostridium terminal subterminal- B.subtilis
88
What is endospore locations used for
characterize/identify species - they do not ever change
89
Spore layers
core core wall inner membrane cortex outer membrane inner/outer coat (exosporium
90
Core
dehydrated Contains only calcium diacid, NO WATER
91
core wall
turns into cell wall when converted to vegetative cell
92
inner membrane
germinate receptors
93
cortex
makes up most of spore volume made up of specialized peptidoglycan that is not fully cross-linked- heat-resistant
94
outer membrane
semi-permeable
95
inner/outer coat
highly structured Acts as a physical barrier
96
exosporium
only found in some species similar to S-layer adds another layer of protection
97
Sporulation
Process of endospore formation All-or-nothing response: once it is triggered you cannot reverse It is tightly regulated Complex multistage process that occurs in up to 10 hours
98
Regulation of sporulation
Master regulator= SpO0A If phosphorylated then sporulation will complete
99
Steps of sporulation
Actin filament formation: - DNA stretches length; some will be degraded and some moved to spore Septum formation and forespore development Engulfment of forespore - Septum membrane engulfs forespore Cortex formation Coat synthesis Completion of coat syntheis - Increase in refractility and heat resistance Lysis of sporangium and spore liberation - Kills mother spore
100
Germination
Reverse of sporulation Triggered by nutrient-rich environments - Nutrients bind to nutrient receptors Transformation of endospore into vegetative cell All-or-nothing response Complex multistage process
101
Three stages of germination
Activation Germination Outgrowth
102
Activation stage
triggers a population of spores homogenously (at same time) Prepares spore for germination Often, results from heating
103
germination stage
“peeling back layers” Environmental nutrients are detected Spore swelling and rupture-spore coat is absorbed - Water rushes in and calcium dicloacid rushes out- triggering metabolic activity Loss of resistance Increased metabolic activity
104
Outgrowth stage
the emergence of vegetative cell lysis of spore coat
105
Species
a group of strains sharing common features while differing considerably from other strains
106
genus
group of closely related species
107
Hierarchy of taxonomy
phylum (broad) class order family genus species (narrow

MCB 2610 (24 decks)

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