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Microbiology > Bacteriology lecture 1 > Flashcards

Bacteriology lecture 1 Flashcards

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Biology 101 flashcards
1
Q

What is the estimated amount of microbial cells on earth?

A

~5 million trillion trillion (10^30)

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2
Q

What is the professors favorite bug?

A

Listeria

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3
Q

Phylogeny

A

Science dealing with evolutionary relationships between living organisms

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4
Q

What is Phylogeny based on?

A

Sequence of macromolecules such as DNA, RNA and protein - Phylogenetic trees

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5
Q

What are the 3 phylogenetic distinct lineages of cells?

A 
2 Prokaryotic (Eubacteria and Archea)
1 Eucaryotic
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6
Q

Who came up with Endosymbiont Theory?

A

Lynn Margulis

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7
Q

What was the Endosymbiont Theory?

A

A major organizational event in the history of life probably involved the merging of two or more lineages through symbiosis.

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8
Q

Single-celled prokaryotic microorganisms and their DNA is not contained within a separate nucleus as in eukaryotic cells are?

A

Bacteria

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9
Q

What characteristic are used to classify and identify bacteria?

A

Shape and size

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10
Q

Approximate size of bacteria

A

0.1-10.0 um in size

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11
Q

Bacteria, bacillus/bacilli means

A

Rods (little stick)

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12
Q

Coccus/Cocci means

A

Round

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13
Q

Pleomorphic means

A

Bacteria which can assume many shapes

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14
Q

What give spirochete the more pronounced shape?

A

Internal flagella

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15
Q

Strepto means

A

chain

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16
Q

Diplococci means

A

two coccus

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17
Q

Tetrad means

A

four

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18
Q

Staphylo means

A

cluster

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19
Q

What divides bacteria individual from the environment?

A

Cell wall

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20
Q

Cell wall is present in all eubacteria except?

A

Mycoplasmas

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21
Q

In prokaryotic cell’s wall is located?

A

Outside the plasma membrane

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22
Q

Most archaeobacteria do not have a cell wall, but those that do have?

A

A different type of peptidoglycan or protein

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23
Q

Functions of the cell wall?

A

Prevents osmotic lysis, protects cell from external stress (host), contributes to virulence, target for antimicrobials

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24
Q

What is a cell wall?

A

Rigid structure surrounding the cell membrane

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25
Q

Two ways of characterize a bacteria cell wall

A

Gram stain

Acid fast stain

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26
Q

The four characterizations of the bacteria cell wall

A

Gram-positive
Gram-negative
Acid Fast
Wall-less

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27
Q

What is the chief structural & composition component of a eubacteria’s cell wall?

A

Peptidoglycan

28
Q

Peptidoglycans are composed of?

A

Long chains of polysaccharides (glycan) cross-linked by short proteins (peptides)

29
Q

The constitution of the polysaccharide is by what two repeating subunits?

A

N-acetyl glucosamine and N-acetyl muramic acid

30
Q

When polysaccharide chains are cross-linked by peptides and then linked together create the?

A

Single rigid mesh-like molecule that forms the cell wall (chain link fence)

31
Q

What determines the major difference between gram + and gram -?

A

Peptidoglycans in the cell wall

32
Q

Gram neg peptidoglycans

A

Mesh is only one layer thick

33
Q

Gram posit peptidoglycans

A

Wall is many layers thick (40)

34
Q

Staining

A

The appearance of bacteria following the gram stain is also used for Identification

35
Q

Purple/blue stained bacteria are?

A

Gram-Positive

36
Q

Gram-Negative bacteria stain?

A

Pink/red

37
Q

The difference in response to the Gram stain results form the ?

A

Composition of the cell envelope

38
Q

What is the unique structure for Gram-neg bacteria?

A

Lipopolysaccharide (LPS)

39
Q

What is an advantage of lipopolysaccharide in Gram-neg?

A

Major permeability barrier

40
Q

Where do Gram-neg bacteria store degradative enzymes?

A

In the periplasmic space

41
Q

Gram-pos bacteria secrete what? and why?

A

exoenzymes and preform extracellular digestion

42
Q

Where is the periplasmic space?

A

Between the lipopolysaccharide membrane and peptidoglycan membrane.

43
Q

What are the two staining methods?

A

1) Simple stain - Basic dyes

2) Differential Stain - combination of basic dyes

44
Q

Basic dyes

A

Have a positive charge and bind to negatively charged bacteria at ~pH-7

45
Q

Acidic dyes

A

Have a negative charge and stain background

46
Q

Gram staining procedure

A 
Fixation
Crystal Violet (primary stain)
Iodine treatment
Decolonization (alcohol/acetone)
Counter stain with Safranin
47
Q

If you get Coccus with pink stain what have you done?

A

Very few Gram-neg Coccus. You have left the stain in the decolonization too long.

48
Q

Acid fast staining procedure

A

Carbol fuchsin
Acid alcohol decolorizer
Counterstain malchite green or methylene Blue
Rest the dilute acid

49
Q

Difference between acid fast and non acid fast bacteria?

A

Acid fast will remain the same color as the first stain used. Non acid fast will show up with a blue color.

50
Q

What is responsible for Acid Fast staining?

A

The mycobacterial cell wall contains long chain length fatty acids (mycolic acids and waxes) which contribute to virulence.

51
Q

Teichoic Acid and Lipoteichoic acid

A

Appear to extend the surface of the peptidoglycan layer in Gram-Positive Bacteria

52
Q

What does Teichoic Acid do?

A

Provide rigidity to the cell wall
Assist in regulation of cell growth
Receptor molecules for some Gram-Positive bacteriophage

53
Q

How does Teichoic Acid provide rigidity to the cell wall?

A

By attracting cations such as magnesium and sodium.

54
Q

How does Teichoic Acid assist in regulation of cell growth

A

By limiting the ability of autolysins to break the Beta (1-4) bonds between the N-acetyl glucosamine and the N-acetylmuramic acid

55
Q

What is the most important part of Gram-Neg bacteria?

A

Lipopolysaccharide

56
Q

What are the three parts of the Lipopolysaccharide?

A

Lipid A-
Core oligosaccharide
O antigen

57
Q

What does the Lipid A of the Lipopolysaccharide do?

A

Embedded in the membrane is responsible for endotoxin activity

58
Q

What unique about the Lipid A of the Lipopolysaccharide?

A

C14 Fatty Acid *hydroxy myristic acid, phosphates, glucosamine

59
Q

What unique about the Core oligosaccharide of the Lipopolysaccharide?

A

Highly conserved among different bacteria

Unique components -KDO (3-deoxy-D-manno-2-octulosonic) acid and heptose

60
Q

What unique about the O antigen of the Lipopolysaccharide?

A

Presents is species dependent
Composed of repeating units consisting 3 to 4 CHOs polymerized into polysaccharide
Antigenic and highly variable among species and strains

61
Q

What is the most potent immune system activators in the Lipopolysaccharide?

A

Lipid A - Endotoxin

62
Q

What is the test for endotoxin Lipid A?

A

Limulus Amebocyte Lysate (LAL) Test

63
Q

What are the specifics of the LAL test?

A

It is an aqueous extract of the blood cells from the horseshoe crab

64
Q

What plays a critical role in the architecture and impermeability of the cell wall in mycobacteria?

A

Mycolic acid

65
Q

How do we visualize bacteria?

A

Compound light microscope
Dark-field microscope
Fluorescent microscope
Electron microscope

66
Q

What is the difference between Light and Electron microscopes?

A

Light- uses visible light

Electron - uses electron beams

67
Q

What is the difference between Negative and Positive stain?

A

Negative - stains the background

Positive - stains the structures

Microbiology (15 decks)

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