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Lecture 4 Flashcards

1
Q

What percentage of bacteria have a cell wall?

A

90%

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2
Q

What does the bacterial cell wall protect it from

A

Osmotic lysis AND mechanical forces

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3
Q

What is the bacterial cell wall made of

A

Peptidoglycan

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4
Q

What is another name for peptidoglycan

A

Murein

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5
Q

What makes up peptidoglycan

A

NAG, NAM and D-amino acids

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6
Q

What are NAG and NAM

A

Amino sugars

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7
Q

What kind of linkage is between NAG and NAM in peptidoglycan

A

B-1,4-glycosidic linkage

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8
Q

Which of the amino sugars is the short D-amino acid chain attached to

A

NAM

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9
Q

Which of these components of the cell wall gives it its shape: peptidoglycans or MreB

A

MreB!

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10
Q

Describe the steps of cell wall formation for bacteria

A
  1. NAM synthesized in cytoplasm & linked to UDP
  2. NAM is linked to bactroprenol
  3. NAG is added to NAM
  4. Bactroprenol flips NAM and NAG to periplasm
  5. Crosslinking occurs
  6. Bactroprenol flips back
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11
Q

Is bactoprenol hydrophilic, amphiphilic or hydrophobic

A

Bactoprenol is amphiphilic

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12
Q

Which two enzymes can degrade bacterial cell walls?

A

Lysozyme and lysostaphin

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13
Q

How does lysozyme break up peptidoglycan?

A

It breaks the B-1-4-linkage

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14
Q

What is present in tears, saliva, human milk and mucous?

A

Lysozymes

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15
Q

How does lysostaphin break peptidoglycans?

A

It breaks the crossbridges within the peptide chains of certain Staphylococcus bacteria ONLY

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16
Q

What organisms produce antibiotics?

A

Bacteria

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17
Q

What can artificially break down a cell wall

A

Beta-lactam antibiotics

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18
Q

How do beta-lactam antibiotics work?

A

They prevent peptidoglycan crosslinking, weakening cell wall structure.

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19
Q

What is left when the cell wall of a bacterium is gone

A

a protoplast

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20
Q

what happens if a protoplast is left in isotonic conditions

A

It will remain intact, but be amorphous

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21
Q

What happens if a protoplast is left in hypotonic solution

A

Water will rush into the protoplast, and it will rupture

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22
Q

What does the enzyme that some bacteria produce do that makes them antibiotic resistant?

A

An enzyme that can destroy the Beta-lactam ring structure of the antibiotic

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23
Q

What is the name of the drug that scientists can add to the antibiotic that stops the enzyme that breaks the beta-lactam ring

A

Augmentin

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24
Q

What is Augmentin

A

Amoxicillin + Clavulanic acid.

25
What is the action of Clavulanic acid?
Clavulanic acid acts to disrupt beta-lactamase, the enzyme which normally breaks down the beta-lactam ring in amoxicillin
26
Who developed the stain method
Hans Christian Gram
27
Bacteria are separated into gram positive and gram negative. According to Hans Christian Gram's staining method, what colour gram positive bacteria? What colour is gram negative?
Gram negative - pink | Gram positive - purple
28
Describe staining process for bacteria
1) all bacteria are stained crystal violet 2) Iodine added to stabilize colour 3) Alcohol added. Gram negative turns clear, but gram positive stays violet 4) Safranin is re-added. The gram negative bacteria turns pink
29
Gram positive bacteria have ____ periplasmic space
narrow
30
gram positive bacteria have ____ layer of peptidoglycan, around __% of the cells dry weight
thick, 90%
31
What kind of acids do the gram positive cells have in their cell walls, that gram negative cells do not?
Teichoic acids.
32
What is the charge teichoic acids?
Negative
33
Gram negative cells have ____ layer of peptidoglycan, which makes up about ___% of their dry weight
thin, 10%
34
Gram negative cells have a ____ periplasmic space
varying
35
What structure do gram negative cells have the gram positive cells lack
an outer membrane
36
What is the outer membrane of gram negative cells composed of
LPS = Lipopolysaccharides.
37
Why are gram negative bacteria harder to treat than gram positive bacteria
Their cells walls are thinner
38
What three things are LPS comprised of:
Lipid A, Core Polysaccharide & O side chain
39
What does the Lipid A portion of the LPS on the outer membrane of gram negative bacteria do?
It induces a strong inflammatory response
40
Which component of LPS from gram negative bacteria can vary the most
The O side chain
41
How do nutrients get through gram+ bacteria
There are large pores in its peptidoglycan matrix
42
How do nutrients get through gram- bacteria
It has Porin and TonB proteins in its outer membrane which transfer molecules to the periplasmic space, after which they are actively transported to the cytoplasm
43
What are the function of pili on bacterial surfaces
to allow attachment, or to provide twitching motility
44
what is the function of the bacterial capsule
to protect from phagocytes (the hosts immunity) and to form a biofilm to prevent from drying
45
S-layer
To protect from bacteriophage
46
``` What do these categories of flagella mean: monotrichous lophotrichous amphitrichous peritrichous ```
mono - one flagellum at one end lopho - multiple flagella at one end amphi - single flagellum at each end peri - flagella all over
47
What are the three basic pieces of a flagellum
filament of flagellin (5 - 10 micrometers long) hook protein: connecting filament to basal body basal body: produces torque on filament, turning it like a propeller
48
where do bacteria get the energy to spin flagella
PMF (proton motive force)
49
Are flagella simple or complex
Complex
50
What are spirochetes
Nonexternal flagella, that are present in the periplasmic space of some flagella
51
What is another name for spirochetes
axial filaments
52
Spirochetes turn the cell in what kind of motion
corkscrew motion
53
What are the two types of adherence molecules on bacteria`
Pili for conjugation and fimbrae for adherence
54
What forms biofilms
Capsules
55
What are two ways biofilms can help bacteria?
Provide protection | Enhance survival in harsh environs
56
Ex of biofilms:
Dental plaque | Mold
57
Can most bacteria be cultured?
No
58
What style of taxonomic names do we give bacteria?
Genus, Species.

Microbiology (4 decks)

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