Lecture 1: Bacterial Morphology and Structure 1 Flashcards

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1
Q

What are the two most common shapes of bacteria

A
  1. Coccus- sphere/round
  2. Bacillus- rod
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2
Q

What are 4 other common shapes of bacteria

A
  1. Coccobacillus- short rod
  2. Vibrio- comma shape
  3. Spirochete- flexible, thin spiral-shaped rod
  4. Spirillum- rigid, spiral-shaped rod
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3
Q

What does it mean if a bacteria is pleomorphic

A

Has no defined shape, variety of shapes in one species

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4
Q

Identify bacteria shapes 1-6

A
  1. Coccus
  2. Bacillus
  3. Coccobacillus
  4. Vibrio
  5. Spirillium
  6. Spirochete
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5
Q

What is the prefix of bacteria that divides in one plan in a pair

A

Diplo

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6
Q

What is the prefix of bacteria that divides in one plain in a chain

A

Strepto

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7
Q

What is the prefix of a bacteria that divides in 2 planes in a grape like cluster

A

Staphylo

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8
Q

What is the prefix of a bacteria that divides in 2 planes in a packet of 4 cells

A

Tetrads

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9
Q

What is the prefix of a bacteria that divides in 2 planes in packets of 8 cells

A

Sarcina

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10
Q

Identify bacteria based on arrangement and shape

A

Diplococcus

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11
Q

Identify the bacteria based on arrangement and shape

A

Streptococcus

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12
Q

what is the arrangement of this bacteria

A

Staphylo

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13
Q

What is the arrangement of this bacteria

A

Tetrad

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14
Q

What is the arrangement of this bacteria

A

Sarcina

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15
Q

What are the functions of the bacterial cytoplasmic membrane

A

Permeability and transport, site of electron transport chain, excrete toxins, chemotaxis

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16
Q

What are 2 examples of bacteria genera without cell walls

A
  1. Mycoplasma
  2. Ureaplasma
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17
Q

What are the three main types of cell walls

A
  1. Gram negative
  2. Gram positive
  3. Acid fast
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18
Q

In order from left to right identify the types of bacterial cell walls

A

left: gram negative
Middle: gram positive
Right: acid fast

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19
Q

What are the 2 main components all three cell walls have

A
  1. Peptidoglycan
  2. lipoproteins
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20
Q

What is the function of peptidoglycan and lipoproteins

A

Structural support

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21
Q

What 3 parts make up the peptidoglycan layer

A
  1. Backbone: NAG-NAM segments
  2. Set of tetrapeptide chains
  3. Set of peptide cross bridges
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22
Q

Why is peptidoglycan clinically relevant when treating a bacterial infection

A

Can target peptidoglycan layer as it is crucial to cell support, damage it and cell wall loses integrity and can lyse

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23
Q

What enzyme is found in secretions and can weaken the cell integrity by damaging peptidoglycan layer

A

Lysozymes

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24
Q

Gram positive or gram negative: thick peptidoglycan layer

A

Gram positive

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25
Q

What color does gram positive bacteria stain

A

Purple

26
Q

Gram positive or gram negative: thin peptidoglycan layer

A

Gram negative

27
Q

What color does gram negative bacteria stain

A

Red

28
Q

What is the primary stain in a gram stain

A

Crystal violet

29
Q

What is the counter stain in gram stains

A

Safranin (red)

30
Q

What is the periplasmic space and is it typical of gram positive or negative

A

Found in gram negative
Space between inner and outer membranes

31
Q

What does periplasmic space contain

A
  1. Thin peptidoglycan layer
  2. Binding proteins
  3. Transport proteins
  4. Hydrolytic enzymes
32
Q

What is the outer membrane and is it specific to gram negative or positive

A

Specific to gram negative
Bilayered structure: inner layer: resembles cytoplasmic membrane, outer membrane: contains phospholipids and LPS

33
Q

What is the distinct component on the outer membrane of a gram negative bacteria

A

LPS

34
Q

What is the function of the outer membrane

A

Protective permeability barrier to large molecules and hydrophobic molecules, impedes phagocytic destruction

35
Q

What are the 3 components of LPS

A
  1. O-antigen
  2. Core polysaccharide
  3. Lipid A
36
Q

What is/ what is the function the O- antigen

A

Outermost portion of LPS, serves as attachment sites, inhibits phagocytosis, can identify strains

37
Q

What is/the function of the core polysaccharide

A

Attaches O-Antigen to Lipid A

38
Q

What is/the function of Lipid A

A

Virulence factor/toxin of LPS—> endotoxin that produces cytokines and inflammatory mediators that can lead to endotoxic shock

39
Q

Which component of the LPS is responsible for endotoxic shock

A

Lipid A

40
Q

Why are endotoxins clinically relevant in horses

A

Leading cause of equine death—> major part of GI disorders like colic and neonatal foal septicemia

41
Q

Why are endotoxins clinically relevant in cattle

A

Play significant role in laminitis and abomasal displacement

42
Q

Which bacterial cell wall has trimeric porins

A

Gram negative

43
Q

What is the function of a porin

A

Transport of solutes

44
Q

What are the two components only found in gram positive bacteria

A
  1. Teichoic acid (WTA)
  2. Lipoteichoic acid (LTA)
45
Q

Where is teichoic acid anchored to

A

Peptidoglycan

46
Q

Where is lipoteichoic acid anchored to

A

Cell membrane

47
Q

What is the function of teichoic and lipoteichoic acid

A

Adherence to cell host, serves as a virulence factor and can initiate endotoxin like behavior

48
Q

Gram negative or gram positive: release endotoxins

A

Gram negative (gram positive can have endotoxin like effects but has no LPS so not endotoxin)

49
Q

What structure is specific to outer layer of acid fast bacteria cell walls

A

Mycolic acid layer

50
Q

What does the mycolic acid layer consist of

A

Long fatty acid chains and lipids that give waxy coat

51
Q

How are mycolic acids connected to peptidoglycan layer

A

Via arabinogalactan

52
Q

What is the function of mycolic acid layer

A

Provides resistance to dessiccation and some antibiotics, inhibits phagocytosis

53
Q

What bacterial cell wall has tetrameric porins

A

Acids fast bacteria

54
Q

What are two clinically relevant genera that are acid fast

A
  1. Mycobacterium
  2. Nocardia
55
Q

What is the primary stain in acid fast

A

Carbolfuschin (acid fast-red)

56
Q

What is the counter stain in acid fast

A

Methylene blue (nonacid-blue)

57
Q

What are the steps in acid fast staining

A
  1. Primary stain-carbolfuschin (acid fast-red)
  2. Heat
  3. Acid-alcohol wash-depolarization
  4. Counterstain- methylene blue (non-acid fast)
58
Q

In this acid fast stain, what is A and B, and which one is acid fast bacteria

A

A. Staphylococcus (grape like clusters, round)
B. Mycobacterium- acid fast- red

59
Q

A stained tracheal mucus specimen collected from a cattle shows acid fast bacilli. Which of the following genera should be included in your differential diagnosis:
A. Clostridium
B. Bacillus
C. Staphylococcus
D. Mycobacterium

A

D. Mycobacterium

60
Q

A foal was diagnosed with endotoxemia caused by endotoxins released into bloodstream. The bacterial cell wall structure causing the patients symptom is which of the following:
A. Lipid A
B. O antigen
C. Teichoic acid
D. Lipoprotein

A

A. Lipid A

61
Q

Gram negative or positive: sensitive to penicillin

A

Gram positive more susceptible

62
Q

Gram negative or positive: sensitivity to lysozymes

A

Gram positive yes