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MICRO > L7: Introduction to Mycology > Flashcards

L7: Introduction to Mycology Flashcards

1
Q

Are fungi eukaryotic or prokaryotic?

Photosynthetic or nonphotosynthetic?

A

Eukaryotic

Nonphotosynthetic

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2
Q

Cell walls of fungi contain what? 2

Describe each

A
  1. Beta-glucans (D-glucose polymer)

2. Chitin (polysaccharide chain of NAG)

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3
Q

Plasma membranes of fungi contain what?

What do animal PM’s have?

A

Ergosterol

Cholesterol

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4
Q

Do Fungi use sexual or asexual reproduction?

A

Both

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5
Q

Are fungi haploid or diploid?

A

Both
Haploid = lower fungi
Diploid = higher fungi

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6
Q

Two forms of fungi? Define each

A
  1. Yeast: Single celled

2. Mold: Multicelliular

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7
Q

For molds, the principal element of vegetative growth is what?

A

Hypha

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8
Q

Hyphae in terms of structure can be categorized how? (2)

A
  1. Septate: Divided by partitions

2. Coenocytic: hollow and multinucleate

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9
Q

In terms of where they grow, how can hyphae be categorized?

A
  1. Aerial = Above surface and are reproductive

2. Vegetative = Below surface and absorb nutrients

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10
Q

How do yeast reproduce?

A
  1. Nuclear fission

2. Budding

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11
Q

What are colonies of masses of intertwining hyphae called?

A

Mycelia

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12
Q

Dimorphic fungi can do what?

A

Be a yeast or a mold depending on environment

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13
Q

When are dimorphic fungi a yeast?

A

Physiologic temperature and abundant nutrients

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14
Q

When are dirmophic fungi mold like?

A

Ambient temperatures and when conditions are not optimal.

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15
Q

When do dimorphic fungi produce spores?

A

When in mold-state

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16
Q

Do most fungi do sexual or asexual reproduction?

A

Most can do both

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17
Q

What is the basis for traditional fungal classification?

A

Sexual reproduction: Spores made and structures used

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18
Q

Mucormycetes or Zygomycetes form what in reproduction?

A

Hyphal fusion results in Zygospore

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19
Q

Describe a zygospore

A

Stalk of sporangiophore with sporangium on top in which haploid zygospores form.

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20
Q

Ascomycetes do what in sexual reproduction?

A

Neighboring segments fuse to form an ascus. Nuclei fuse, undergo meiosis, then mitosis to form ascospores

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21
Q

What group of fungi are the largest group of human pathogens?

A

Ascomycetes

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22
Q

Upon fusing together, what is the status of zygomycete ploidy?

A

Diploid

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23
Q

Basidiomycetes have what for sexual reproduction?

A

Basidiosporespores develop in basidium and migrate to surface before release

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24
Q

Deuteromycetes do what for sexual reproduction?

What are they similar to?

A

No sexual stage observed,

Most are similar to asomycetes

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25
Q

Asexual spores have what two names?

A

Sporangiospores

Conidia

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26
Q

What does it mean if spores are sporangiospores?

A

They are contained in a structure

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27
Q

What does it mean if spores are conidia?

A

Born naked on specialized structures

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28
Q

What two types of spores form by fragmentation of hyphae?

Differentiate the two

A
  1. Arthospores: Rectangular

2. Chlamydospores: Circular

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29
Q

Blastospores form how?

What form are they usually in?

A

By budding

Yeast

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30
Q

Five categories of pathogenic fungi?

A 
Superficial
Cutaneous
Subcutaneous
Systemic
Opportunistic
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31
Q

Are most people resistant to pathogenic fungi?

A

yes

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32
Q

Resistance factors to pathogenic fungi include? (4)

A
  1. Fatty acids
  2. pH
  3. Epithelial cell turnover
  4. normal flora
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33
Q

Superficial mycoses have what effect?

A

Cosmetic, no physical discomfort

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34
Q

Superficial mycoses infect what?

A

Nonliving tissue

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35
Q

How do you treat superficial mycoses? 2

A
  1. Keratolytic agents

2. Shaving

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36
Q

Cutaneous mycoses are restricted to what tissues?

A

Keratinized tissues such as nails, hair, and stratum corneum

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37
Q

Most cutaneous mycoses are what type of parasites?

A

Obligate human parasites

38
Q

Can cutaneous mycoses be transmitted person to person?

A

Yes

39
Q

What is the collective name for cutaneous mycoses species

A

Dermatophytes

40
Q

How does susceptibility vary for cutaneous mycoses? 2

A
  1. Demogrpahics of patient

2. Footwear and clothing

41
Q

Cutaneous mycoses begin where?
How do they spread
Based on how they are spread, what are they called? 2

A

Cornified layer of skin

Ringworm or tineas

42
Q

Cutaneous mycoses induce what? 2

A

Cellular respones and inflammation

43
Q

What is the most fatal type of mycoses?

A

Subcutaneous mycoses

44
Q

Two examples of subcutaneous mycoses?

A

Sporotrichosis

Chromoblastomycosis

45
Q

How do you get a subcutaneous mycoses?

A

Trauma lets it in

46
Q

What is Rose Gardener’s Disease?

A

When a rose thorn causes trauma allowing spores into subcutaneous tissue

47
Q

Systemic mycoses are in what form at physiologic temperature?
At ambient temperature?

A

Yeasts

Molds

48
Q

Systemic fungi live in what environments?

Specifically what types of habitats?

A

Alkaline

Bat and bird feces

49
Q

How are systemic mycoses acquired?

What is the primary site of infection?

A

Inhalation

Lungs

50
Q

What are most systemic mycoses symptoms?

A

Asymptomatic or mild

51
Q

Systemic mycoses have a tendency to cause what?

A

Granuloma formation

52
Q

How are systemic mycoses restricted?

A

By geography

53
Q

Opportunistic mycoses require what?

A

A hampered immune system

54
Q

Opportunistic mycoses will be seen when what happens? 6

A
  1. Debilitation
  2. endocrine problems
  3. Cancer of WBC’s
  4. Immunosuppression
  5. Antibiotics
  6. X-irradiation
55
Q

Opportunistic mycoses are typically what?

A

Environmental saprophytes or normal body flora

56
Q

Oral thrush is usually the result of what? (2)

A
  1. Long term antibiotic

2. Immunosuppression

57
Q

Mycotoxins are seen in what two species?

A
  1. Amanita mushrooms

2. Aspergillus

58
Q

Amanita mushroms make what two important hepatotoxins?

A
  1. Amanitin

2. Phalloidin

59
Q

Aspergillus makes what?

How do you acquire this?

A

Aflatoxins

Eating spoiled grains and peanuts

60
Q

Lab diagnosis of mycoses is done how?

A 
Culture
Microscope
Immune response/Serology
Examination of tissue samples
Nucleic Acid PCR
61
Q

What is the common medium for culture lab diagnosis?

What is the relative speed of fungi growth?

A

Sabouraud’s agar

Slow

62
Q

What do you look for in tissue samples?

A
  1. Hyphae, yeast forms in tissue treated with KOH or special stains
  2. Antigen detection by ELISA
63
Q

The telltale sign of fungus is what?

A

KOH treatment: destroys human tissue but doesn’t harm fungal

64
Q

What are the fungal targets for drugs? 5

A
  1. Cell wall = inhibiting glucan synthesis
  2. Cell membrane = inhibiting ergosterol syn
  3. Cell membrane = damage
  4. Nucleus = Disruption of microbutules and inhibition of mitosis
  5. Nucleus = Inhibit nucleic acid synthesis
65
Q

Polyenes in clude what?

A

Amphotericin B and Nystain

66
Q

Polyenes target what and bind to this?

A

Ergosterol

67
Q

Polyene binding to ergosterol cause what?

A

Produce ion channel that destroys osmotic integrity of cell membrane –> Death

68
Q

Amphotericin B does what?

A

As a polyene, it binds to ergosterol, forms an ion channel, and disrupts potential.

69
Q

Nystain does what?

A

Binds to ergosterol

70
Q

How is nystain used?

Why?

A

Topically

Toxic

71
Q

The Azoles do what?

A

Shut down synthesis of ergosterol

72
Q

Two types of azoles are based on what?

A

Number of nitrogen atoms in azole ring

73
Q

Two types of azoles are what?

A
  1. Imidazoles (2 nitrogens)

2. Triazoles (3 nitrogens)

74
Q

Azoles target what enzyme?

A

cytochrome p450 dependent lanosterol 14-alpha-demethylase

75
Q

What is the most famous allyamine?

A

Lamisil

76
Q

Allylamines are used for what?

A

Broad spectrum against dermatophytes

77
Q

What is the mechanism of allylamine action?

A

Inhibit squalene epoxidase that decreases ergosterol and increases squalene

78
Q

How is allylamine used?

A

Topically or oral

79
Q

Echinocandins are what type of molecules?

A

Lipopeptides

80
Q

What is mechanism of echinocandins?

A

Inhibit synthesis of Beta-(1,3)-glucans which are part of cell wall.

81
Q

Are echinocandins static or cidal?

A

Either or depending on fungus

82
Q

Main side effect of echinocandins?

A

GI upset

83
Q

What does flucytosine disrupt?

A

Nucleic acid synthesis?

84
Q

Structure of flucytosine?

A

Fluorinated pyrimidine analogue.

85
Q

What does flucytosine become in the cell?

Which allows it do what?

A

5-FU and

competes with uracil in RNA

86
Q

What makes flucytosine special?

A

Water soluble and gives high concentrationsin CSF, serum and fluids

87
Q

Is flucytosine used alone mainly?

A

No, because of secondary resistance

88
Q

Griseofulvin acts on what fungi?

A

Dermatophytes

89
Q

Mechanism of griseofulvin action?

A

Interferes with microtubules in the nucleus causing inhibition of mitosis

90
Q

What are the resistance mechanisms to antifungals?

A
  1. Changes in target
  2. loss of permeability
  3. efflux pumps

MICRO (22 decks)

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