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Physiology of Microbes > Bacterial Motility L10 > Flashcards

Bacterial Motility L10 Flashcards

1
Q

which bacteria are usually non-motile

A

cocci

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2
Q

which bacteria are usually motile

A

bacillus and spiral cells

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3
Q

what does motility require

A

cell surface structures

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4
Q

how is bacterial motility distinguished

A

brownian motion

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5
Q

is gonorrhea motile

A

round cocci cell motile

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6
Q

how is bacterial movement regulated

A

environmental stimuli

  • induction of movement
  • direction of movement
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7
Q

what are the forms of bacterial motility

A

swarming
twitching
gliding

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8
Q

what is the name for bacteria with a single flagellum at 1 pole

A

monotrichious

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9
Q

what is the name for bacteria with a cluster at one pole

A

lophotrichious

lopho = tuft, multiple hairs

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10
Q

what is the name for bacteria with a single/cluster at both poles

A

amphotrichious

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11
Q

what is the name for bacteria with even distribution over surface

A

petritrichious

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12
Q

what is trichious

A

hair

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13
Q

how can flagellae be seen

A

too thin for light microscope

need electron micrograph or staining to make the flagellae thicker

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14
Q

how long are flagellae

A

at least as long as cell

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15
Q

what makes up the flagellum

A

filament
hook
basal body

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16
Q

what is the filament function in the flagellum

A

act as a propeller

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17
Q

what is the hook function in the flagellum

A

connects filament to motor

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18
Q

what is the basal body function in the flagellum

A

motor to turn whole flagellum round

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19
Q

what do the rings do in the flagellum structure

A

acts as washers

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20
Q

where is the basal body

A

spans cytoplasmic membrane and outer membrane

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21
Q

what does the basal body do

A

forms a specialised type of secretion complex

acts as a secretion pore, allow flagellum to be made in the cell and pass out so filament can be made outside

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22
Q

what is the gram negative bacteria flagellum like

A

basal body has 3 rings connected by a rod:

  • SM ring embedded in cytoplasmic membrane
  • P ring interacts with peptidoglycan layer
  • L ring interacts with outer membrane
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23
Q

what is the gram positive bacteria flagellum like

A

basal body consists of SM ring and rod
no L ring
P ring much thicker as not got outer membrane just a thick layer of peptidoglycan

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24
Q

what happens once the basal body is formed

A

subunits for the hook assembled on outside of cell

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25
what does the hook do for movement in cell
acts as an articulation joint to allow narrow helix to form during rotation produces a tight spiral - good for powering cells forward
26
what is added to the Hook
end of hook defined by HAPs hook associated proteins | proteins put on end
27
what are the hook associated proteins used for
prevent it being a leaky pore, select movement
28
how is the flagellum assembled
basal body at bottom rings on top motor surrounds the proteins of the basal body Flagellin added to the distal end (furthest away from the surface of the cell) HAP2
29
how does the flagellin pass out of the cell, and its growth
cell through the hook Passed HAPs Flagellin added to the distal end (furthest away from the surface of the cell) HAP2 form cap, controls addition of new flagellin subunits as grows
30
how are flagellum made
cells continually renew flagellum
31
where are the motor proteins located
below and around the SM ring
32
how does the cell have energy to move
energy for rotation of flagellum comes from cellular proton motive force (needs ATP)
33
how does the motor turn
H+ ions pass through periplasm into motor proteins into cell one of the subunits of the motor proton = one turn of the motor ring like an electrostatic meter
34
where are sheathed bacteria
found in spirochetes located between cell wall and outer sheath attached to one end of organism
35
how does the sheathed bacteria move
axial filaments turned, whole cell turns creating a corkscrew movement through liquid
36
when are swarmer cells made
Triggered to turn from swimmer to swarmer due to torque If motor clicks round and something stops flagellae turning, knows on surface not liquid, makes torque If flagella cant turn = torque (stress) knows not in a liquid medium, so turn into swarm cell
37
what is the difference between a swarmer cell and a swimmer
swarmer cells – increase massively the number of flagellae they make and become much longer, become multinucleate
38
what happens in swarmer cell process, what causes long swarmer cells
elongate, copy nucleic acid, at end of process cell division – if inhibit the cell division without inhibiting other = long swarmer cells
39
what do swarmer cells look like when moved on agar
rings from centre out
40
can swarmers convert back into swimmer cells
go back into liquid phase and torque stop, turn back into swimmer cells – completely reversible
41
examples of bacteria with twitching motility
``` Pseudomonas bacteria (gram -ve rod) Neisseria gonococcus (gram -ve coccus) ```
42
what is required for twitching motility
polar type 4 (fimbriae) pili | - fine hair like structures (6nm x 1-10um) formed from pilin protein
43
where does twitching motility occur
on surfaces | adhesion role to surfaces and host cells (virulence)
44
how do cells move when twitching motility
in intermittent or 'jerky' manner either singly or small aggregates
45
what are specialised pili for
plasmid transfer in conjugation
46
how is the pilus assembled
proteins at interface of cytoplasmic membrane and outer membrane, control assembly of flagellum subunits brought into cytoplasmic membrane, sucked up into the PilQ complex – controls their assembly pool of subunits in periplasmic space, can pulled on anytime to extend the pilus pilus built outwards
47
what subunits make up the pilus
polymerisation ofPilA protein
48
pilus disassembly
unlike flagellum process is reversible (two way system) | need to continually add subunits to the pilus and pull them out and put somewhere – need to be in the pool
49
what causes the movement in twitching motility
movement induced by retraction of pilus pili extended out is tight, starts to retract pilus move towards where attached
50
what does twitching motility look like on agar
spreading zones on edge of colony | edge of colony has “ground glass” appearance
51
what does twitching motility require
alternative sigma factor for expression
52
what are the three modes that require surface filament production
swarming swimming twitching
53
which bacteria was gliding first identified in
cyanobacteria
54
where does gliding motility occur
only occur on surfaces; relatively slow
55
what changes in cell when gliding motilityoccurs
no change in cell morphology BUT cells have specialised cell wall structures to secrete mucilage
56
how does gliding motility move cell
pili at one end pull cells in one direction (S engine) | A engine slime pushes
57
what is necessary for gliding motility - engine slime used to push forward
extracellular slime made by junctional pore complex | need S layer (crystalline protein encasing outer membrane)
58
how do some cells control direction movement
helical oscillin fibrils (grooved structures on top of S layer)
59
what energy does gliding motility require
``` membrane potential (energised membrane) not ATP ```
60
what controls rate of movement
rate of movement proportional to rate of mucilage secretion
61
where is the junctional pore complex and what occurs here
JPC spans entire Gram negative cell wall, seems to be actual site of slime secretion
62
what does the slime do in gliding motility
slime flows in tight contact with surface of oscillin fibrils and guides rotation of filament
63
how do cells move in gliding motility using the slime
grooves are set diagonally across the cell pumping slime into grooves creates rotational movement oscilin fibrils not on all cells oscilin helps them move forward when want to change direction will change which pump they use
64
what does flagella mediated motility need
flagella assembly
65
what is swarming motility
surface induced change in cell morphology
66
what is twitching motility
uses pili rather than flagellae
67
what is gliding motility
mediated by slime production
68
what is surface spreading
requires secretion complex to secrete surfactant, allow the cells to spread out following growth
69
what do Swarmer cells inhibit
cytokinesis step
70
what are sheathed bacteria similar to
flagella

Physiology of Microbes (21 decks)

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