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Microbiology Exam 1 > Intro to Med Micro > Flashcards

Intro to Med Micro Flashcards

1
Q

Microbiology includes which four types of organisms?

A

1) bacteria
2) virus
3) fungi
4) parasites

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2
Q

Approximately how many cells are in our body? And how many bacteria are in our body?

A

cells in body - 10^14 cells

bacteria in body - 10^15 cells

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3
Q

Which is bigger, viruses or bacteria?

A

bacteria

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4
Q

Which is bigger, bacteria or protozoa/fungi?

A

protozoa/ fungi

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5
Q

Can you see viruses with light microscope?

A

No, electronic microscope is needed

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6
Q

What is the smallest infectious particles?

A

viruses

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7
Q

True or False. Bacteria are multicellular organisms

A

FALSE. they are unicellular

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8
Q

If bacteria are prokaryotes, what about fungi and parasites?

A

fungi and parasites are both eukaryotes

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9
Q

True or False. Fungi are ALL multicellular

A

False. yeast is unicellular

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10
Q

Of the four categories of microorganisms, which is the smallest?

A

viruses

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11
Q

Of the four categories of microorganisms, which is the most complex?

A

parasites

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12
Q

Are parasites unicellular or multicellular?

A

both

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13
Q

What is the difference between eukaryotes and prokaryotes in regards to presence of nucleus?

A

prokaryotes do not have nucleus (bacteria)

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14
Q

True or False. Humans and bacteria utilize the same ribosomes?

A

False. bacteria use a smaller ribosome (70S)

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15
Q

What structure is unique to bacteria?

A

peptidoglycan cell wall

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16
Q

What are some ways to detect bacteria in clinical samples (5)?

A

1) microscopy
2) detection of bacterial antigens
3) detection of bacterial nucleic acids
4) culture - metabolic properties
5) detection of antibody response to bacteria (such as looking for IgM –> primary infection Abs)

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17
Q

What are some ways to classify bacteria (5)?

A

1) visible features
2) nutrition
3) end products
4) surface molecules
5) nucleic acid

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18
Q

What type of visible features are used to classify bacteria?

A

1) shape
2) spore formation
3) Gram reaction

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19
Q

How is nutrition used to classify bacteria?

A

1) growth media
2) aerobic vs. anaerobic
3) temperature required for optimal growth

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20
Q

What are you looking for when using end products to classify bacteria?

A

production of specific enzymes or toxins

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21
Q

What are some surface molecules that can be used to classify bacteria?

A

unique proteins, sugars or lipids - usually cell surface

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22
Q

What is a more rigid classification system currently being delineated?

A

nucleic acid analysis

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23
Q

What shape do cocci have?

A

spherical

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24
Q

What shape do bacilli have?

A

rod - straight or curved

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25
Q

What shape do spirochetes have?

A

spirals

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26
Q

True or False. Both Gram (+) and Gram (-) have peptidoglycan in their cell wall

A

True

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27
Q

A bacteria is Gram (+), what color will it be?

A

purple

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28
Q

A bacteria is Gram (-), what color will it be?

A

reddish, pink

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29
Q

Is peptidoglycan located external or internal to the capsule?

A

internal

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30
Q

Is peptidoglycan located external or internal to cytoplasmic membrane?

A

external

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31
Q

What is the function of peptidoglycan in bacteria?

A

protection against physical/mechanical, osmotic, chemical and biological agents

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32
Q

True or False. peptidoglycan determines shape

A

TRUE

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33
Q

True or False. peptidoglycan makes for a good drug target

A

True, bc it’s not in humans

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34
Q

What are some proinflammatory effects of peptidoglycan?

A

1) fixes complement
2) binds to pattern recognition receptors (ex. toll-like receptors)
3) triggers TNF production (via NFk-B)

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35
Q

Why do Gram (+) bacteria turn purple?

A

the crystal violet is trapped in a thick, cross-linked peptidoglycan layer

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36
Q

What are two components of Gram (+) envelope?

A

1) peptidoglycan

2) teichoic acid

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37
Q

Lipoteichoic acid (LTA) is associated with which structure?

A

plasma membrane

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38
Q

Teichoic acid is associated with which structure?

A

peptidoglycan

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39
Q

What is the purpose of teichoic acid and LTA?

A

promote attachement to other bacteria and to host cells

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40
Q

True or False. Teichoic acid and LTA are specific to Gram (+) bacteria only

41
Q

True or False. Teichoic acid and LTA are important virulence factors for Gram (+) bacteria

42
Q

Why do Gram (-) bacteria turn pink upon Gram staining?

A

they have a thin peptidoglycan layer and do not retain crystal violet thus they are counterstained with saffarin to turn reddish pink

43
Q

True or False. Both Gram (+) and Gram (-) bacteria have two membrane layers

A

False, only Gram (-) bacteria have two layers

44
Q

Gram (-) bacteria are surrounded by an outer membrane rich in _____ and _____

A

1) porins

2) lipopolysaccharide (LPS)

45
Q

Where is peptidoglycan located in Gram (-) bacteria?

A

periplasmic space

46
Q

What is the function of outer membrane of Gram (-) bacteria?

A

maintains structure and permeability barrier (porins)

47
Q

Gram (-) bacteria have an asymmetric phospholipid bilayer, what is in its inner leaflet and what is in its outer leaflet?

A

inner –> phospholipids

outer –> lipopolysaccharide (LPS)

48
Q

What are the three components of LPS?

A

1) lipid A
2) core polysaccharide
3) O antigen

49
Q

Which component of LPS is responsible for endotoxin activity?

50
Q

Which of the three components of LPS is required for bacterial structure and viability?

A

core polysaccharide

51
Q

What is a long, linear polysaccharide of repeating saccharide units of 4 to 7 sugars/unit?

52
Q

How do LPS cause inflammation?

A

bind to CD14 and TLR4 on phagocytes/ APCs –> massive inflammatory response, causing inflammation and could cause septic shock

53
Q

Which cytokines are responsible for septic shock (3)?

A

1) TNF
2) IL-1
3) IL-6

54
Q

True or False. Acid-fast bacteria do not contain peptidoglycan

55
Q

What long, branched fatty acid is associated with acid-fast bacteria?

A

mycolic acids

56
Q

What is responsible for the thick waxy membranous layer of acid-fast bacteria?

A

mycolic acids

57
Q

What stain is used for acid-fast stain?

A

carbol fuchsin

58
Q

What is used in the decolorization step of acid-fast stain?

A

acid alcohol

59
Q

What is used to counter-stain in acid-fast stain?

A

methylene blue

60
Q

What’s the function of mycolic acid?

A

impedes entry of chemicals/lysosomal enzymes which leads to a fastidous slow growing bacteria

61
Q

Structure of acid-fast bacteria is similar to Gram (+) or Gram (-) bacteria?

62
Q

Do acid fast bacteria have an outer membrane?

63
Q

What are the three components of acid fast cell wall?

A

1) lipoarabinomannan (LAM)
2) arabiogalactans
3) mycolic acid

64
Q

Which of components of acid fast cell wall is functionally similar to LPS?

65
Q

Arabinogalactans are branched polysaccharides that bind to _____

A

mycolic acid

66
Q

What are molecular hair-like projections on surface of both Gram (+) and Gram (-) cells?

67
Q

Pilin forms a tube with a small ____ core

68
Q

Pili/ fimbrae are composed of protein subunits called ____

69
Q

What are the two functional types of pili

A

1) common (somatic)

2) sex

70
Q

Which type of pili is involved in attachment to epithelial cells

71
Q

What is also called adhesins, lectins, evasins and aggressins?

A

common pili

72
Q

Which type of pili is involved with gene transfer?

73
Q

How many sex pili are usually present in each cell?

74
Q

What are rotating helical structures anchored to plasma membrane responsible for locomotion?

75
Q

What structure is H-antigen associated with?

76
Q

What structure is K-antigen associated with?

77
Q

Are H and K antigens important virulence factors?

A

you-betcha!

78
Q

What is also known as slime layer?

79
Q

What’s the function of capsules?

A

aides in protection from immune system

1) poorly antigenic
2) antiphagocytic

80
Q

Are capsules important for culture? What about survival in host?

A

culture - not important

host survival - important

81
Q

What is an organized community of microbial cells that has a capsule/ slime layer over the entire population?

82
Q

What reaction can be used to identify capsules?

A

Quellung reaction

83
Q

If capsules are present, what occurs when anti-capsular antibodies are added in Quellung reaction?

A

the capsules will swell

84
Q

How are encapsulated bacteria removed from body?

A

opsonized and cleared by spleen

85
Q

What can be used as an antigen in vaccines against encapsulated bacteria?

A

capsules + protein conjugate

86
Q

Which type of bacteria can become endospores: Gram (+) or Gram (-)?

A 
some Gram (+)
never Gram (-)
87
Q

Under what conditions are endospores formed?

A

harsh environments

88
Q

Bacteria convert from a vegetative state to a ____ state

89
Q

When does germination of endospores occur?

A

favorable environmental conditions

90
Q

True or False. An endospore gives rise to a single bacteria once the conditions become favorable

91
Q

Which of the following statements are true regarding endospores?

1) highly resistant to enviromental stressors
2) can exist for centuries
3) spores can be aerosolized

A

All 3 statements are true

92
Q

What kind of structure do endospores have?

A

dehydrated, multishelled

93
Q

What are the contents of an endospore (3)?

A

1) one complete copy of chromosome
2) minimum concentration of proteins and ribosomes
3) high concentration of calcium bound to dipicolinic acid

94
Q

Describe the inner membrane of endospores

A

2 peptidoglycan layers

95
Q

Describe the outer coat of endospores

A

keratin-like protein

96
Q

What sterilization technique must be done to rid of endospores?

A

autoclave, 120 degrees celsius at high pressure for >20 min

97
Q

Can endospores withstand attacks by enzymes and chemicals?

98
Q

A patient presents with a flulike illness (fever, chills, headache, cough, myalgias and chest pain). Analysis of a sputum sample by phase-contrast microscopy reveals intracellular spherical forms of about 8 µm diameter with a single nucleus. The causative agent of the infection is likely a ____

Microbiology Exam 1 (10 decks)

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