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MICRB 201 > Quiz 3 > Flashcards

Quiz 3 Flashcards

1
Q

What are the two main systems of surface motility?

A

Twitching and Gliding

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2
Q

How is twitching motility facilitated?

A
  • requires type 4 Fimbriae that extend from 1 pole of the cell, attach to a surface, and retract to pull the cell forward
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3
Q

How does twitching motility allow cells to move together in groups?

A

-production of type 4 fimbriae
-secretion of extracellular polysaccharides = good for cell cohesion

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4
Q

T/F, twitching motility only exhibited in bacteria and not archaea

A

F. In many bacteria and some archaea

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5
Q

What kind of movement does twitching motility exhibit

A

Choppy, less fluid movement

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6
Q

How is gliding motility facilitated?

A

Exact mechanism not well known but current consensus:
- gliding motor proteins associate with the helical track causing rotation. -the movement of motor proteins somehow transferred to surface adhesion proteins causing movement in helical direction

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7
Q

Three main components of gliding motility

A
  • Helical intracellular protein track in loop around cell
  • Gliding motors: rotary motors driven by proton motive force
    -Adhesion proteins: grab on surfaces outside the cell
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8
Q

What kind of movement does gliding motility exhibit

A

-smooth motion along the long axis of cell without the use of external structures
-continuous/ cohesive movement

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9
Q

T/F gliding motility is observed in bacteria but not archaea

A

True

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10
Q

What type of motion does periplasmic flagella exhibit

A

more rigid motion, corkscrew motlility

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11
Q

why is corkscrew motility in periplasmic flagella beneficial?

A
  • organisms with these flagella tend to move through more viscous environments and need the rigid motion
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12
Q

What are periplasmic flagella and what is their structure?

A

-In spirochetes
-refers to space after the cell membrane and before the cell wall
-Internal flagella system
-Amphitrichous with tufts intertwined and folded back lining the surface of the organism forming an axial filament

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13
Q

How does pathogenic bacteria interact with host cell actin for motility within a host cell?

A
  • pathogen gets into the host
    -pathogen breaks out, dispersing host cell actin filaments
    -pathogen uses actin filaments for its own motility means using the protein it contains to aggregate filaments
    -Pathogenic access to the host filament allows movement to other cells and projection from 1 host cell to the next
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14
Q

What are the benefits to a pathogen/ virus utilizing within host cell motility

A

-easier for pathogen to evade immune system if it is travelling from host cell to host cell

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15
Q

4 types of motility

A

-Gliding
-Twitching
-Within the host cell
-corkscrew motility within periplasmic flagella

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16
Q

Similarities between prokaryotic cytoskeleton and eukaryotic cytoskeleton

A

-MreB (prok) similar to Actin microfilaments (euk)
-FtsZ (prok) similar to tubulin in microtubules (euk)

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17
Q

What are the three proteins in the prokaryotic cytoskeleton? What are they used for?

A

-used to mediate the binary fission process:
-MreB
-FtsZ
-Crescentin (CreS)

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18
Q

T/F specialized structures in prokaryotes are membrane-bound organelles

A

false

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19
Q

4 types of specialized prok structures

A
  1. Thylakoids
  2. Carboxysomes
  3. Gas vesicles
  4. Magnetosomes
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20
Q

Thylakoids

A

-series of folded sheets of membrane containing chlorophyll and electron carriers needed for ATP synthesis
-overall, dense system around the cell to absorb light energy (photosynthesis)

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21
Q

Carboxysomes

A

-Poly hedral shape with a protein covering packed with rubisco
-Rubisco: need for C02 fixation in photosynthesis

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22
Q

Gas vesicles

A

-in planktonic bacteria
-permeable to gas, impermeable to water
-filled with gas helps with buoyancy allowing bacteria to get to better light source

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23
Q

2 proteins in Gas vesicles

A

-GvpA and GvpC

24
Q

Magnetosomes

A
  • Allows for motility
    -Aggregate magnetic type
    -allows organisms to move along earths magnetic pole
25
Internal structures of bacteria
-Cytoplasm -Nucleoid -Plasmids -Ribosomes
26
Nucleoid
-Area of the cell where DNA is aggregated -compact/ condensed chromosome structure
27
Plasmids
-extrachromosomal pieces of DNA -Dont aggregate as well with chromosomes
28
Ribosomes
-Sites of protein synthesis -rRNA found in all organisms -difference between euk and pork are types of ribosomes expressed
29
Eukaryotic ribosomal subunits
-60S large -40S small -80S combined
30
Prokaryotic ribosomal subunits
-50S large -30S small -70S combined
31
What does S stand for when describing ribosomes?
-Svedberg unit- for understanding sedimentation rate under acceleration
32
Why are ribosomal subunits relevant?
-making proteins/ knowing how ribosomes in prok vs euk work -knowing how antibiotics work: some antibiotics meant to inhibit ribosomal activities, need to make sure antibiotics only affect pathogen ribosomes and not ours
33
What provides as an example of bacteria differentiating into different cell types
Endospores
34
What are Endospores
-Highly differentiated dormant cells (in dormant stage of bacterial cell life cycle) -Withstand high temp, radiation, various chemicals and can survive millions of years in this state -Easily dispersed and only grow in favorable conditions
35
What 2 Gram + types of bacteria in Firmicute phylum produce endospores
-Bacillales (baccilus) used for bio terrorism -Clostridiales (Clostridium) related to contamination in canning -Both: found in soil, also can be major cause of foodborne disease and food spoilage
36
Sporulation
process of cellular differentiation resulting in endospores
37
General process of sporulation
-Start : highly refactile free endospore -Activation -Germination - outgrowth
38
Activation
-spore becomes less refractile as spore is hydrated. Prepares spore for germination
39
Germination
-spore begins to develop into a vegetative cell -spore swells, spore coat ruptures, release of spore components and loss of resistance
40
Outgrowth
-makes new cell components and emerges from spore remains -vegetative cell emerges and starts division
41
List endospore structure inside to outside
-Core -Inner spore membrane -Cortex -Outer spore membrane -Endospore coat -sometimes exosporium
42
What is used to stain an endospore
malachite green infused into endospore using steam
43
Core
-innermost region of endospore -contains DNA and ribosomes -Develops from cytoplasm in vegetative cell -Metabolically inactive when significantly dehydrated (less that 10-25% H20) -Dipicolinic acid and calcium dehydrate
44
Inner spore membrane
-surrounds core -develops from cytoplasmic membrane and serves as cells plasma membrane
45
Cortex
-surrounds inner spore membrane -composed of loosely linked peptidoglycan
46
Outer spore membrane
-surrounds cortex
47
Endospore coat
-surrounds outer membrane -4-5 layers of endospore specific proteins
48
Exosporium
-outermost layer -Proteinaceous layer (not in all endospores) -thin protein weaving layer
49
Why are endospores so tough?
1. Dehydration of core (Dipicolinic acid) -dipicolinic acid accumulated. binds to H20 to dehydrate endospore. -acid inserts between DNA bases = stabilizing DNA from denaturation 2. High levels of small acid-soluble spore proteins (SASP) -bind to DNA in core and make more compact =protect from heat, radiation and desiccation damage -serve as carbon and energy source for outgrowth of vegetative cell from endospore during germination
50
Storage bodies
granules of organic/ inorganic material that function to store molecules/ structural building blocks
51
typical energetic molecules/ nutrient building block storage bodies
1. Poly-beta-hydroxybutyric acid 2. Glycogen 3. Polyphosphate 4. Elemental sulfur
52
Poly-beta-hydroxybutyric acid
-made when cell comes into high carbon area -broken down when in low carbon area
53
Glycogen
-made when carbon in high-access -polymer of glucose
54
Polyphosphate
-made when phosphate in high-access
55
Elemental sulfur
-Stores elemental sulfur -in sulfur bacteria that use oxidized sulfur as energy source
56
Sporulation process
1. Free endospore process 1: Germination 2. Vegetative cycle -growth -cell division process 2: Asymmetric cell division leads to 3. Stage 2: mother cell - engulfs prespore, builds cortex -process 3: engulfment -outer spore membrane formed from mother cell cytoplasmic membrane 4. Stage 3 process 4: cortex formation 5. stage 4 -cortex, cytoplasmic membrane, cell wall process 5: dehydration spore, Ca2+ uptake, SASPs, Dipicolinic acid 6. Stage 5 process 6: maturation, cell lysis 7. Stage 6 and 7

MICRB 201 (3 decks)

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