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Microbiology 1010 > Lecture 2- Flagella and swimming motility > Flashcards

Lecture 2- Flagella and swimming motility Flashcards

1
Q

what is the lifecycle of a spore forming bacterium

A

stage 1: asymmetric cell division (DNA replicates, identical chromosomes pulled to opposite ends of the cell)

stage 2: septation (divides cell into two unequal compartments; forespore (prespore) and mother cell)

stage 3: mother cell engulfs the forespore (forespore surrounded by two membranes)

stage 4: formation of the cortex (thick layers of peptidoglycan form between the two membranes)

stage 5: coat synthesis (protein layers surround the core wall –> spore coat, exosporium) Ca+ and SASP accumulates in the core to stabilize DNA

stage 6: endospore matures (core is dehydrated to make it more heat stable)

stage 7 mother cell is lysed (mother cell disintegrates, mature spore is released)

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2
Q

what is the general structure of flagella?

A

hollow protein filaments

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3
Q

do flagella need to be stained?

A

yes! with flagella stain

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4
Q

what are the 4 types of flagella?

A

monotrichous
amphitrichous
lophotrichous
peritrichous

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5
Q

what is monotrichous?

A

single flagellum

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6
Q

what is amphitrichous?

A

flagella at opposite ends

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7
Q

what is lophotrichous?

A

multiple flagella in a single tuft

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8
Q

what is peritrichous?

A

flagella distributed around cell

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9
Q

what are the 3 components to flagellar structure?

A

filament
hook
basal body (motor)

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10
Q

what is the filament of a flagella?

A

rigid helical protein
composed of identical protein subunits called flagellin

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11
Q

what is the hook of a flagella?

A

flexible coupling between filament and basal body

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12
Q

what is the basal body of a flagella?

A

its a central rod that passes through a series of rings

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13
Q

what are the 4 rings apart of the basal body in the flagella?

A

L ring: LPS layer
P ring: peptidoglycan
MS ring: membrane
C ring: cytoplasm (associated with membrane)

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14
Q

what energy does the flagella use to turn?

A

proton motive force

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15
Q

how does the proton motive force work with flagellar movement?

A

gradient of protons across the cytoplasmic membrane high proton outside
low proton inside
most proteins form a channel that allows H+ to move into the cytoplasm, this provides the energy to turn the flagellum

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16
Q

how does the flagellum move?

A

turns counterclockwise like a propeller to drive the cell forward

17
Q

what is required for flagellar synthesis?

A

several genes are required for flagellar synthesis and motility

18
Q

in what order does the flagella grow?

A

MS ring is made first
other proteins and hook are made next
filament grows from tip

19
Q

how do peritrichously flagellated cells move?

A

slowly in a straight line

20
Q

how do polarly flagellated cells move?

A

more rapidly and typically spin around

21
Q

what is gliding motility?

A

flagella independent motility that requires surface contact through glide proteins

22
Q

what 3 mechanisms are apart of gliding motility?

A

excretion of polysaccharide slime (decreases slime)
type IV pili (used to help in motility)
gliding specific proteins

23
Q

what is a taxis?

A

directed movement in response to chemical or physical gradients

24
Q

what are the 5 specific types of taxis?

A

chemotaxis
phototaxis
aerotaxis
osmotaxis
hydrotaxis

25
Q

what is chemotaxis?

A

response to chemicals

26
Q

what does chemotaxis do?

A

responds to temporal (not spatial) difference in chemical concentration

27
Q

how do chemotaxis move?

A

run and tumble
they have directed movement toward an attractant or away from a repellent

28
Q

how is a chemotaxis a biased random walk?

A

goes in a straight line (run) when it feels its getting close to the attractant but every couple seconds it tumbles and faces another direction

29
Q

how do chemotaxis know theyre attracted to something?

A

by chemoreceptors

30
Q

what is an example of chemotaxis?

A

E. coli shows biased random walk toward glucose when there is a concentration gradient. the cell will exhibit a series of runs and tumbles, if it senses that the glucose is increasing/ close the tumble is delayed and the run lasts longer

31
Q

does the run and walk ever stop?

A

no, even when right beside attractant, flagella never stop moving

32
Q

how do you measure chemotaxis?

A

by inserting a capillary tube containing an attractant or a repellant in motile bacteria
can also be seen under a microscope

33
Q

what is phototaxis?

A

response to light

34
Q

what is aerotaxis?

A

response to oxygen

35
Q

what is osmotaxis?

A

response to ionic strength

36
Q

what is hydrotaxis?

A

response to water

Microbiology 1010 (19 decks)

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