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Microbiology > Lecture 4: Microbial Physiology > Flashcards

Lecture 4: Microbial Physiology Flashcards

1
Q

What are the three basic shapes of prokaryotic cells?

A
  • rod
  • coccus
  • spirillum
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2
Q

What size are prokaryotic cells?

A

1-5 micrometers

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3
Q

Additional morphologies of prokaryotic cells

A
  • Star shaped: stella
  • rectangular Haloarcula (Archaea)
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4
Q

Pleomorphic Bacteria Shapes

A

Rhizobium and Corynebacterium

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5
Q

Largest bacteria ever

A

Thiomargarita Magnifica

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6
Q

Cell wall

A
  • peptidoglycan
  • Sugar chains cross linked by peptides
  • Cell wall building/turnover during growth and division can influence cell shape
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7
Q

Turgor Pressure

A
  • Cells contain lots of stuff-DNA, proteins, sugars,
    salts
  • If cells are in an aqueous (watery) environment,
    the surrounding medium has less stuff in it
  • Because of this disparity, water tends to flow into
    the cells, results in turgor pressure
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8
Q

Rod Shaped

A
  • bacilli (bacillus is a genus name)
  • G+ and G- rods
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9
Q

What axis do bacilli divide?

A

divide along narrow axis

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10
Q

Streotiobacilli

A

long chains of rods

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11
Q

diplobacilli

A

pairs of rods attached end to end

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12
Q

coccobacilli

A

very short rods, almost cocci

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13
Q

vibrios “curved rods”

A
  • Vibrio cholerae the agent of cholera
  • In the book described as spiral bacteria, but phylogenetically aligned with G- rods
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14
Q

cocci

A

sphere
- gram negative and positive

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15
Q

different cocci have ___ division planes

A

different

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16
Q

What possible advantage is there to being rod or spirillum shaped vs. cocci?

A

The way they associate with surfaces is different. Rod shaped has more contact with the surface than spheres. The way they stack/pack is also more beneficial.

17
Q

Streptococci

A

divide along a single plane, form chains

18
Q

Staphylococci

A

divide along all planes, form clumps

19
Q

how do other cocci divide?

A

form tetrads and sarcinae, as well as pairs (diplococci)

20
Q

Spirillum

A
  • one or two turns around helical axis
  • external flagella
21
Q

Spirochete

A
  • flagella sheathed, run along length of cell
  • “corkscrew motility”
  • Borrellia Burgdorferi (Lyme disease) , treponema pallidum (syphilis)
22
Q

Prokaryote Physiology

A
  • Cell Membrane
  • Outer membrane
  • Cell wall (peptidoglycan)
  • Exopolysaccharide matrix
  • Flagella
  • Pili and Fimbriae
  • Genome Structure
  • Ribosomes
23
Q

Overall Bacterial Structure

A
  • External structures
    (pili, flagella, fimbriae)
     Outer Membrane G-
    only
     Cell wall
    (peptidoglycan sacculus or wall)
     Cell membrane
     Cytosol
24
Q

3 parts of Flagella

A

3 parts
- filament (made of the protein flagellin)
- hook (different protein)
- Basal body

25
Q

Flagellar Assembly

A
  • flagellin subunits travel up through the middle of the flagellum, to the growing tip
  • similar, evolutionarily related to Type III secretion important in pathogenesis.
26
Q

_____ flagella-distributed over cell body

A

Peritrichous

27
Q

On cell surface, flagella can also be at….

A

the poles

28
Q

monotrichous

A

single at one end

29
Q

lophotrichous

A

clump of flagella at one end

30
Q

Amphitrichous

A

flagella at both ends

31
Q

Spirochete Flagella

A
  • Very cool structure
     Doesn’t emerge from the cells
     Cool propulsion mechanism
     Cryoelectron tomography
32
Q

Are all bacteria motile?

A

No

33
Q

Types of motility

A
  • Tumble and swim
    chemotaxis
  • “gliding motility”
  • Spirochete corkscrew motility
33
Q

Fimbriae

A
  • generally smaller and spread throughout a cell
  • Fimbriae-protein filaments on cell outer surface
  • Either at poles or evenly distributed
  • Important in cell attachment to surfaces
  • Well studied in Neisseria gonorrhoeae
  • Fimbriae are a virulence factor for enteric, urogenital pathogens
34
Q

What do bacteria secrete/their pathways?

A
  • make proteins to be exported to periplasm and
    surroundings
  • Sec pathway (general secretion)
  • Sec independent (type II)
  • Type III (virulence)
  • there are 10 known secretion pathways
34
Q

pilus/pili

A
  • generally larger/longer and more sparse on the cell
  • involved in cell-cell attachment
    phenomena, in preparation for DNA
    transfer (conjugation)
  • Pili are sometimes the site of attachment for bacteriophages, viruses that infect bacteria
35
Q

Exopolysaccharide (EPS) Matrix (glycocalyx)

A
  • Environmental bacteria often live on surfaces covered in EPS
  • Called a biofilm
  • In pathogenic microbes, this is often called the slime capsule
  • An important defense against the immune
    system
  • A virulence factor, esp. for G+ cocci pathogens
36
Q

S. Pneumoniae Capsule

A
  • Streptococci are known for the production of capsule
  • Primary component
    hyaluronic acid
  • Mutants that don’t make capsule are avirulent
  • This was used to prove that DNA is the genetic material
    (1941)
37
Q
A

Microbiology (16 decks)

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