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Microbiology > Lecture 4 > Flashcards

Lecture 4 Flashcards

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Biology 101 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
Q

What is the action of Clavulanic acid?

A

Clavulanic acid acts to disrupt beta-lactamase, the enzyme which normally breaks down the beta-lactam ring in amoxicillin

26
Q

Who developed the stain method

A

Hans Christian Gram

27
Q

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?

A

Gram negative - pink

Gram positive - purple

28
Q

Describe staining process for bacteria

A

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
Q

Gram positive bacteria have ____ periplasmic space

A

narrow

30
Q

gram positive bacteria have ____ layer of peptidoglycan, around __% of the cells dry weight

A

thick, 90%

31
Q

What kind of acids do the gram positive cells have in their cell walls, that gram negative cells do not?

A

Teichoic acids.

32
Q

What is the charge teichoic acids?

A

Negative

33
Q

Gram negative cells have ____ layer of peptidoglycan, which makes up about ___% of their dry weight

A

thin, 10%

34
Q

Gram negative cells have a ____ periplasmic space

A

varying

35
Q

What structure do gram negative cells have the gram positive cells lack

A

an outer membrane

36
Q

What is the outer membrane of gram negative cells composed of

A

LPS = Lipopolysaccharides.

37
Q

Why are gram negative bacteria harder to treat than gram positive bacteria

A

Their cells walls are thinner

38
Q

What three things are LPS comprised of:

A

Lipid A, Core Polysaccharide & O side chain

39
Q

What does the Lipid A portion of the LPS on the outer membrane of gram negative bacteria do?

A

It induces a strong inflammatory response

40
Q

Which component of LPS from gram negative bacteria can vary the most

A

The O side chain

41
Q

How do nutrients get through gram+ bacteria

A

There are large pores in its peptidoglycan matrix

42
Q

How do nutrients get through gram- bacteria

A

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
Q

What are the function of pili on bacterial surfaces

A

to allow attachment, or to provide twitching motility

44
Q

what is the function of the bacterial capsule

A

to protect from phagocytes (the hosts immunity) and to form a biofilm to prevent from drying

45
Q

S-layer

A

To protect from bacteriophage

46
Q 
What do these categories of flagella mean:
monotrichous
lophotrichous
amphitrichous
peritrichous
A

mono - one flagellum at one end
lopho - multiple flagella at one end
amphi - single flagellum at each end
peri - flagella all over

47
Q

What are the three basic pieces of a flagellum

A

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
Q

where do bacteria get the energy to spin flagella

A

PMF (proton motive force)

49
Q

Are flagella simple or complex

A

Complex

50
Q

What are spirochetes

A

Nonexternal flagella, that are present in the periplasmic space of some flagella

51
Q

What is another name for spirochetes

A

axial filaments

52
Q

Spirochetes turn the cell in what kind of motion

A

corkscrew motion

53
Q

What are the two types of adherence molecules on bacteria`

A

Pili for conjugation and fimbrae for adherence

54
Q

What forms biofilms

A

Capsules

55
Q

What are two ways biofilms can help bacteria?

A

Provide protection

Enhance survival in harsh environs

56
Q

Ex of biofilms:

A

Dental plaque

Mold

57
Q

Can most bacteria be cultured?

A

No

58
Q

What style of taxonomic names do we give bacteria?

A

Genus, Species.

Microbiology (4 decks)

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