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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
Asexual spores have what two names?
Sporangiospores | Conidia
26
What does it mean if spores are sporangiospores?
They are contained in a structure
27
What does it mean if spores are conidia?
Born naked on specialized structures
28
What two types of spores form by fragmentation of hyphae? | Differentiate the two
1. Arthospores: Rectangular | 2. Chlamydospores: Circular
29
Blastospores form how? | What form are they usually in?
By budding | Yeast
30
Five categories of pathogenic fungi?
``` Superficial Cutaneous Subcutaneous Systemic Opportunistic ```
31
Are most people resistant to pathogenic fungi?
yes
32
Resistance factors to pathogenic fungi include? (4)
1. Fatty acids 2. pH 3. Epithelial cell turnover 4. normal flora
33
Superficial mycoses have what effect?
Cosmetic, no physical discomfort
34
Superficial mycoses infect what?
Nonliving tissue
35
How do you treat superficial mycoses? 2
1. Keratolytic agents | 2. Shaving
36
Cutaneous mycoses are restricted to what tissues?
Keratinized tissues such as nails, hair, and stratum corneum
37
Most cutaneous mycoses are what type of parasites?
Obligate human parasites
38
Can cutaneous mycoses be transmitted person to person?
Yes
39
What is the collective name for cutaneous mycoses species
Dermatophytes
40
How does susceptibility vary for cutaneous mycoses? 2
1. Demogrpahics of patient | 2. Footwear and clothing
41
Cutaneous mycoses begin where? How do they spread Based on how they are spread, what are they called? 2
Cornified layer of skin Ringworm or tineas
42
Cutaneous mycoses induce what? 2
Cellular respones and inflammation
43
What is the most fatal type of mycoses?
Subcutaneous mycoses
44
Two examples of subcutaneous mycoses?
Sporotrichosis | Chromoblastomycosis
45
How do you get a subcutaneous mycoses?
Trauma lets it in
46
What is Rose Gardener's Disease?
When a rose thorn causes trauma allowing spores into subcutaneous tissue
47
Systemic mycoses are in what form at physiologic temperature? At ambient temperature?
Yeasts Molds
48
Systemic fungi live in what environments? | Specifically what types of habitats?
Alkaline Bat and bird feces
49
How are systemic mycoses acquired? | What is the primary site of infection?
Inhalation Lungs
50
What are most systemic mycoses symptoms?
Asymptomatic or mild
51
Systemic mycoses have a tendency to cause what?
Granuloma formation
52
How are systemic mycoses restricted?
By geography
53
Opportunistic mycoses require what?
A hampered immune system
54
Opportunistic mycoses will be seen when what happens? 6
1. Debilitation 2. endocrine problems 3. Cancer of WBC's 4. Immunosuppression 5. Antibiotics 6. X-irradiation
55
Opportunistic mycoses are typically what?
Environmental saprophytes or normal body flora
56
Oral thrush is usually the result of what? (2)
1. Long term antibiotic | 2. Immunosuppression
57
Mycotoxins are seen in what two species?
1. Amanita mushrooms | 2. Aspergillus
58
Amanita mushroms make what two important hepatotoxins?
1. Amanitin | 2. Phalloidin
59
Aspergillus makes what? | How do you acquire this?
Aflatoxins Eating spoiled grains and peanuts
60
Lab diagnosis of mycoses is done how?
``` Culture Microscope Immune response/Serology Examination of tissue samples Nucleic Acid PCR ```
61
What is the common medium for culture lab diagnosis? | What is the relative speed of fungi growth?
Sabouraud's agar Slow
62
What do you look for in tissue samples?
1. Hyphae, yeast forms in tissue treated with KOH or special stains 2. Antigen detection by ELISA
63
The telltale sign of fungus is what?
KOH treatment: destroys human tissue but doesn't harm fungal
64
What are the fungal targets for drugs? 5
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
Polyenes in clude what?
Amphotericin B and Nystain
66
Polyenes target what and bind to this?
Ergosterol
67
Polyene binding to ergosterol cause what?
Produce ion channel that destroys osmotic integrity of cell membrane --> Death
68
Amphotericin B does what?
As a polyene, it binds to ergosterol, forms an ion channel, and disrupts potential.
69
Nystain does what?
Binds to ergosterol
70
How is nystain used? | Why?
Topically | Toxic
71
The Azoles do what?
Shut down synthesis of ergosterol
72
Two types of azoles are based on what?
Number of nitrogen atoms in azole ring
73
Two types of azoles are what?
1. Imidazoles (2 nitrogens) | 2. Triazoles (3 nitrogens)
74
Azoles target what enzyme?
cytochrome p450 dependent lanosterol 14-alpha-demethylase
75
What is the most famous allyamine?
Lamisil
76
Allylamines are used for what?
Broad spectrum against dermatophytes
77
What is the mechanism of allylamine action?
Inhibit squalene epoxidase that decreases ergosterol and increases squalene
78
How is allylamine used?
Topically or oral
79
Echinocandins are what type of molecules?
Lipopeptides
80
What is mechanism of echinocandins?
Inhibit synthesis of Beta-(1,3)-glucans which are part of cell wall.
81
Are echinocandins static or cidal?
Either or depending on fungus
82
Main side effect of echinocandins?
GI upset
83
What does flucytosine disrupt?
Nucleic acid synthesis?
84
Structure of flucytosine?
Fluorinated pyrimidine analogue.
85
What does flucytosine become in the cell? | Which allows it do what?
5-FU and | competes with uracil in RNA
86
What makes flucytosine special?
Water soluble and gives high concentrationsin CSF, serum and fluids
87
Is flucytosine used alone mainly?
No, because of secondary resistance
88
Griseofulvin acts on what fungi?
Dermatophytes
89
Mechanism of griseofulvin action?
Interferes with microtubules in the nucleus causing inhibition of mitosis
90
What are the resistance mechanisms to antifungals?
1. Changes in target 2. loss of permeability 3. efflux pumps

MICRO (22 decks)

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