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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
Q

Internal structures of bacteria

A

-Cytoplasm
-Nucleoid
-Plasmids
-Ribosomes

26
Q

Nucleoid

A

-Area of the cell where DNA is aggregated
-compact/ condensed chromosome structure

27
Q

Plasmids

A

-extrachromosomal pieces of DNA
-Dont aggregate as well with chromosomes

28
Q

Ribosomes

A

-Sites of protein synthesis
-rRNA found in all organisms
-difference between euk and pork are types of ribosomes expressed

29
Q

Eukaryotic ribosomal subunits

A

-60S large
-40S small
-80S combined

30
Q

Prokaryotic ribosomal subunits

A

-50S large
-30S small
-70S combined

31
Q

What does S stand for when describing ribosomes?

A

-Svedberg unit- for understanding sedimentation rate under acceleration

32
Q

Why are ribosomal subunits relevant?

A

-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
Q

What provides as an example of bacteria differentiating into different cell types

A

Endospores

34
Q

What are Endospores

A

-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
Q

What 2 Gram + types of bacteria in Firmicute phylum produce endospores

A

-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
Q

Sporulation

A

process of cellular differentiation resulting in endospores

37
Q

General process of sporulation

A

-Start : highly refactile free endospore
-Activation
-Germination
- outgrowth

38
Q

Activation

A

-spore becomes less refractile as spore is hydrated. Prepares spore for germination

39
Q

Germination

A

-spore begins to develop into a vegetative cell
-spore swells, spore coat ruptures, release of spore components and loss of resistance

40
Q

Outgrowth

A

-makes new cell components and emerges from spore remains
-vegetative cell emerges and starts division

41
Q

List endospore structure inside to outside

A

-Core
-Inner spore membrane
-Cortex
-Outer spore membrane
-Endospore coat
-sometimes exosporium

42
Q

What is used to stain an endospore

A

malachite green infused into endospore using steam

43
Q

Core

A

-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
Q

Inner spore membrane

A

-surrounds core
-develops from cytoplasmic membrane
and serves as cells plasma membrane

45
Q

Cortex

A

-surrounds inner spore membrane
-composed of loosely linked peptidoglycan

46
Q

Outer spore membrane

A

-surrounds cortex

47
Q

Endospore coat

A

-surrounds outer membrane
-4-5 layers of endospore specific proteins

48
Q

Exosporium

A

-outermost layer
-Proteinaceous layer (not in all endospores)
-thin protein weaving layer

49
Q

Why are endospores so tough?

A
  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
Q

Storage bodies

A

granules of organic/ inorganic material that function to store molecules/ structural building blocks

51
Q

typical energetic molecules/ nutrient building block storage bodies

A
  1. Poly-beta-hydroxybutyric acid
  2. Glycogen
  3. Polyphosphate
  4. Elemental sulfur
52
Q

Poly-beta-hydroxybutyric acid

A

-made when cell comes into high carbon area
-broken down when in low carbon area

53
Q

Glycogen

A

-made when carbon in high-access
-polymer of glucose

54
Q

Polyphosphate

A

-made when phosphate in high-access

55
Q

Elemental sulfur

A

-Stores elemental sulfur
-in sulfur bacteria that use oxidized sulfur as energy source

56
Q

Sporulation process

A
  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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