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CELS 191 > Lecture 27: introduction to Prokaryotic cells > Flashcards

Lecture 27: introduction to Prokaryotic cells Flashcards

1
Q

the cell wall of bacteria is…

A

peptidoglycan

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2
Q

function of Bacteria cell wall:

A
  • rigid macromolecular layer that provides strength to cell

- protect cell from osmotic lysis and confers cell shape

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3
Q

prokaryotes that lack cell walls are…

A

mycoplasmas

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4
Q

what are mycoplasmas?

A

group of pathogenic bacteria

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5
Q

peptidoglycan is in a…

A

mesh-like structure

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6
Q

Transpeptidase is…

A

the enzyme that cross-links the peptidoglycan chains to form rigid cell walls

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7
Q

the structure of peptidoglycan:

A
  • NAG/NAM
  • side chains amino acids
  • cross bridge amino acids
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8
Q

gram stain procedure produces:

A
  • gram-negative bacteria in red

- gram positive bacteria in purple

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9
Q

gram stain procedure:

step 1 -

A

application of crystal violet (purple dye)

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10
Q

gram stain procedure:

step 2 -

A

application of iodine (mordant)

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11
Q

gram stain procedure:

step 3 -

A

alcohol wash (decolorisation)

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12
Q

gram stain procedure:

step 4 -

A

Application of safranin (counterstain)

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13
Q

Structure of a gram-positive bacteria cell wall:

A
  • cell wall (peptidoglycan layer)

- plasma membrane

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14
Q

the peptidoglycan layer in gram-positive bacteria is…

A

thick

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15
Q

thick peptidoglycan traps…

A

crystal violet, which masks the red safranin dye

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16
Q

structure of a gram-negative bacteria cell wall:

A
  • cell wall (outer membrane/peptidoglycan)

- plasma membrane

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17
Q

the peptidoglycan layer in gram-negative bacteria is…

A

thin

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18
Q

in the thin layer of peptidoglycan crystal violet is…

A

easily washed away, revealing the red safranin dye

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19
Q

motile bacteria produce…

A

flagella

20
Q

flagella are long flexible…

A

appendage resembling “tails”

21
Q

flagella act like…

A

a propeller, cell rotates them to move through a liquid medium

22
Q

number and location of flagella on a cell…

A

can very

23
Q

3 Major sections of flagella:

A
  • long filament
  • hook
  • basal body
24
Q

long filament structure of flagellum:

A
  • extends into surrounding medium
  • composed of subunits
    (protein = flagellin)
25
Q

Hook structure of flagellum:

A
  • curved section connecting the filament to the cell surface
26
Q

basal body structure of flagellum:

A
  • anchors flagellum into cell membrane
27
Q

how are flagellum anchored into the cell membrane:

A

by special disc-shaped structures called plates or rings

28
Q

tactical response moving in response to environment

A

chemotaxis

29
Q

positive chemotaxis:

A

bacteria move along concentration gradient towards a chemical attractant

30
Q

negative chemotaxis:

A

bacteria move away from a chemical repellent

31
Q

temporal gradients are:

A

change in chemical concentrations outside the cell over time

32
Q

Bacterial adherance factors:

A

glycocalyx

  • capsules
  • slime layers
33
Q

glycocalyx is a…

A
  • gelatinous polysaccharide

- or polypeptide outer covering

34
Q

glycocalyx forms a…

A

sticky meshwork of fibres

35
Q

glycocalyx organised into a defined structure attached firmly to cell wall is…

A

capsule

36
Q

glycocalyx disorganised without cell shape, attached loosely to cell wall is…

A

slime layer

37
Q

glycocalyx capsules can serve numerous functions including:

A
  • virulence factors
  • adhere to cell surfaces and structures
  • prevent cell from drying out (desiccation)
38
Q

virulence factors is:

A

protecting bacteria from phagocytosis and engulfment by immune cells

39
Q

example of capsule adherence:

A

to medical implants and catheters

40
Q

bacterial endospores are formed during…

A

unfavourable growth conditions

41
Q

bacterial endospores germinate under…

A

favourable conditions

42
Q

bacterial endospores protects cells from…

A

stress

43
Q

bacterial endospores are only present in…

A

some gram positive bacteria

- members of the genus bacillus

44
Q

endospores are…

A

highly differentiated cells

45
Q

endospores are resistant too:

A
  • heat
  • harsh chemicals
  • antibiotics
  • disinfectants
  • radiation
46
Q

endospores can stay dormant…

A

for a very long time

CELS 191 (31 decks)

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