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LSCI 230 > Bacteria and Archaea > Flashcards

Bacteria and Archaea Flashcards

1
Q

What are the possible shapes of bacteria?

A

coccus, rod, spirillum, spirochete, budding/appendaged, filamentous

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2
Q

What is the purpose of cell walls?

A

allow bacteria to withstand intracellular osmotic pressure, responsible for shape and rigidity

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3
Q

What are the steps of a Gram’s stain?

A
  1. flood heat fixed smear with crystal violet for 1 min (all cells purple)
  2. add iodine solution for 1 min (all cells purple)
  3. decolonize with alcohol for ~20s (Gram positive=purple, Gram negative=clear)
  4. counterstain with safranin for 1-2 min (Gram positive = purple, Gran negative = red/pink)
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4
Q

Why is the colour different in Gram positive and negative cells?

A

Gram positive and negative both have a peptidoglycan layer but Gram negative also have an outer membrane which is the reason for the colour difference

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5
Q

What is peptidoglycan?

A

polymer of peptidoglycan with many known variations

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6
Q

What is another name for peptidoglycan?

A

meurin

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7
Q

What are the subunits of peptidoglycan?

A

NAG and NAM (sugars), short peptide chains containing D amino acids, NAM and DAP (never found in eukaryotes or archaea)

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8
Q

What is the backbone of peptidoglycan made up of?

A

polymerized sugars (NAM and NAG)

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9
Q

What is lysozyme?

A

secreted in tears/saliva/other bodily fluids, protects the body against pathogens, works to hydrolyze the bonds in the peptidoglycan sugar backbone

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10
Q

What provides rigidity in peptidoglycan?

A

In one direction it is provided by the polymerization, in the other it is provided by bonds between adjacent peptides on adjacent peptidoglycan

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11
Q

Gram negative have ___ cross linking while Gram positive have ___ cross linking

A

direct/interbridge

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12
Q

what is another name for cross linking?

A

transpeptidation

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13
Q

Describe the characteristics of the Gram positive cell wall

A
  • up to 90% peptidoglycan
  • teicholic acid and lipoteicholic acid (composed of glycerol-P or ribitol-P) combined with a.a. and sugar covalently bonded to the peptidoglycan
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14
Q

What is sortase?

A

the enzyme that covalently attaches wall associated PRO to the peptidoglycan

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15
Q

Describe the characteristics of the Gram negative cell wall

A
  • 5-10% peptidoglycan
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16
Q

What is the periplasm?

A

space between cytoplasmic and outer membrane, contains peptidoglycan and a high quantity of PRO with specific functions

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17
Q

What is another name for the periplasm?

A

PRO gel

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18
Q

What is the outer membrane?

A

atypical bilayer (phospholipids inside and phospholipid and liposaccharides outside)

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19
Q

What is the outer layer of the outer membrane called?

A

The LPS layer

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20
Q

Describe the LPS layer

A

lipid A linked to a polysaccharide by 2-ketodeoxyoctonate

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21
Q

What is lipid A?

A

lipid moiety, toxic to animals (causing inflammation and sepsis), and endotoxin that plays a major role in pathenogenesis of Gram negative bacteri, contains 6 lipid tails embedded in the membrane

22
Q

What is O-specific polysaccharide?

A

aka O-antigen; consists of repeating sequence of 2-4 monosaccharides, its diversity is key in the diversity of bacterial strains

23
Q

Cell walls of archaea contain no ___ and usually have no ___. They may consist of ___, ___, or ___

A

peptidoglycan/outer membrane/PRO/polysaccharides/glycoproteins

24
Q

What is pseudomeurin?

A

similar in structure to peptidoglycan/meurin but with N-acetyltalosamine-uronic acid instead of NAM and lacking D amino acids

25
Q

Is the linkage between sugars in archaea susceptible to lysozyme?

A

No

26
Q

some species of archaea have cell walls composed of repeating units of two or more sugars (___) but most consist of ___ and/or ___

A

heteropolysaccharides/PRO/glycoPRO

27
Q

What is an S-layer?

A

aka the paracrystalline layer, in archaea it is a cell wall with a crystalline appearance, can also be in bacteria on top of the peptidoglycan or outer membrane

28
Q

what is the capsule/slime layer?

A

synthesized by some bacteria/archaea as extra protection, doesn’t add significant strength to the wall, sometimes covalently bonded to the outer membrane or peptidoglycan layer, important in determining virulence (protects against host defences)

29
Q

What makes up the capsule/slime layer?

A

polysaccharides or PRO, either heteropolysaccharides (most bacteria) or homopolysaccharides (some Gram negative)

30
Q

What are flagella or fimbriae used for?

A

motility

31
Q

one flagella=___, many flagella spread across the surface=___, many flagella on one end=___

A

monotrichous/peritrichous/lophotrichous

32
Q

What are the rings of a Gram positive flagella?
What are the rings of a Gram negative flagella?
(order the from bottom to top)

A
  • C-ring, MS-ring, P-ring

- C-ring, MS-ring, P-ring, L-ring

33
Q

What powers the flagella movement?

A

proton motive force in the motor PRO and fil PRO

34
Q

What are the steps of biosynthesis of a flagella?

A
  1. C and MS-ring form
  2. Motor PRO form
  3. P-ring forms
  4. L-ring forms
  5. Early hook forms
  6. Late hook and cap form
  7. filament synthesizes between hook and cap
35
Q

What are the types of movement of bacteria?

A
  1. peritrichous: bundled flagella spin CCW, tumble CW, the spin CCW again
  2. polar:
    a. reversible flagella: CW to CCW
    b. unidirectional flagella: CW, reorient, CW
36
Q

Describe gliding motility

A

movement along a surface, either music secretion, lateral movement of surface adhesions, or type IV plus-dependant

37
Q

Describe taxis

A

directed movement toward or away from a gradient of chemical or physical agents

38
Q

What are the types of taxis?

A

chemotaxis (chemicals/nutrients/antibiotics), phototaxis (light), aerotaxis (oxygen), osmotaxis (ionic strength)

39
Q

If theres no attractant present there is ___ movement, if there is an attractant present there is ___ movement

A

directed/random

40
Q

What are fimbriae?

A

primarily involved in attaching microbe to surface, they form rigid, rod-like structures primarily in G negative

41
Q

Describe fimbriae in G negative

A
  • grow from the base
  • anchored in outer membrane
  • composed of piling
  • not covalent, strand exchange
  • needs accessory PRO coded with piling gene)
42
Q

Describe fimbriae in G positive

A
  • anchored in peptidoglycan
  • composed of piling PRO
  • covalently linked together
  • assembled enzymatically (sortase)
43
Q

What is an endospore?

A

highly differentiated ells that are extremely resistant to harsh environments, in dormant stage, easily dispersed

44
Q

What are the parts of the endospore?

A

exosporium (PRO), spore coat (layers of spore-specific PRO), cortex (peptidoglycan), core/cytoplasm (Ca2+, DPA, SASPS), DNA, core wall

45
Q

What is SASPS?

A

small acid-soluble spore PRO; bind ton DNA and protect it from damage (UV)

46
Q

What id the purpose of DPA and Ca2+ in the endospore?

A

bind to water to dehydrate the core

47
Q

Core of the endospore contains PRO needed for ___

A

germination

48
Q

What are the steps of the sporulation cycle?

A

stage I: asymmetric division, commitment to sporulation
stage 2: septum divides perspire and mother cell
stage 3: engulfment
stage 4: cortex formation
stage 5: spore coat, Ca2+ uptake, SASPS, DPA
stage 6/7: maturation and cell lysis
germination follows

49
Q

What are cell inclusions?

A

storage for energy reserves and building blocks, can be enclosed by single layer membrane (phospholipid, PRO, glycoPRO)

50
Q

What are the storage nutrients form cell inclusions?

A

C, S, P

51
Q

some cells use inclusions for ___

A

buoyancy

52
Q

What is the name of the cell inclusions that contain magnetite and allow the bacteria to reposed to magnetic fields/

A

magnetosome

LSCI 230 (9 decks)

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