Mycology Lecture 1 Flashcards

(97 cards)

1
Q

Fungi are completely ____ from plants.

A

distinct

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2
Q

True or false: of the 2-4 million fungal species that have been described by taxonomists, a large portion are clinically relevant.

A

False - only about 200 fungal species are known to cause human disease

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3
Q

Fungi are a part of which domain of life?

A

Eukarya

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4
Q

Good fungi are a part of our ___, such as:

A

food; chocolate, bread, beer, cheese, edible mushrooms and truffles

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5
Q

Besides food, how else are fungi beneficial? (5)

A

they are commercially and medically useful:

  1. some fungi convert corn sugars to ethanols for food, and
  2. we have extracted penicillin (antibiotic) from fungal species
  3. can be used for biodegradable packaging
  4. can play a role in cleaning up pollution
  5. fight cancer
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6
Q

Great Potato Famine in Ireland was caused by:

A

Phytophthora infestans

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7
Q

Saint Anthony’s Fire (more common in Middle Ages) is caused by:

A

Claviceps

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8
Q

Symptoms of Saint Anthony’s Fire

A

Hallucinations, confusions, gangrenous limbs, skin sores, convulsions

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9
Q

Derivatives of the toxin produced by ____ is now used in medications, such as migraine meds.

A

Claviceps

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10
Q

About __ fungal species are known to cause human disease. About __% of all human infections are caused by __ ___ species of fungi.

A

200; 90%; a few dozen

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11
Q

True or false: fungal pathogens cause a wide range of infections, such as superficial, cutaneous, subcutaneous, and systemic

A

True

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12
Q

True or false: when a fungal pathogen becomes systemic, often it is easy to cure the infection solely by using antifungal drugs.

A

False - at that stage, the fungi can erode through layers of skin and tissue. The only way to remove the infection is through surgical excision/debridement. In other words, fungal meds on their own will likely not be enough

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13
Q

Fungi are ___ and contain ____

A

eukaryotic; organelles

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14
Q

Fungi are like animals in the sense that they are _____

A

heterotrophs

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15
Q

Fungi require organic compounds for ____ and ____ ____

A

energy and carbon sources

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16
Q

True or false: first fungi ingest their food source and then digest them

A

False - first digest externally, then ingest nutrients

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17
Q

In addition to being heterotrophs, fungi are _____

A

osmiotrophs

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18
Q

A unique biosynthetic pathway found in fungi

A

lysine synthesis

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19
Q

Fungi take on what three morphological forms?

A
  1. yeast
  2. hyphae
  3. both
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20
Q

What is one way that fungi are completely distinct from plants?

A

No chlorophyll

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21
Q

True or false: fungal cell membrane is primarily made of chitin

A

False - cell wall contains chitin

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22
Q

Chitin is useful for providing ___ to fungal cells

A

rigidity

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23
Q

Chitin is similar to ____ ___ in humans

A

hyaluronic acid

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24
Q

Fungal cell wall contains:

A

chitin, glucans, mannans

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25
Fungal cell membranes contain:
ergosterol
26
___ ____ RNA is used in fungal diagnosis
18S ribosomal (18S rRNA)
27
True or false: Fungi are largely anaerobic
False - mainly aerobic (limited anaerobic capabilities)
28
Name 3 fungal "nutritional modes"
1. saprobes 2. parasites 3. mutualists
29
Saprobe
lives on dead materials; decomposers found in the environment
30
Parasites
live on living organisms; pathogens that cause harm to host
31
mutualists
live on host but provide benefits to the host
32
A commonly known parasitic fungus called ____ causes "zombie ants"
Cordyceps
33
Cordyceps pathogenesis in ant
1. invades brain of ant 2. forces ant to walk up to a high point on vegetation 3. kills ant by sprouting from its body (long hyphae type structure) 4. spores are released (aerosolized) to spread to other ants
34
Fungi are non-____, which means the have to reproduce via ____ dissemination of ___
non-motile; passive dissemination; spores
35
True or false: some fungi can produce both asexual and sexual spores
True
36
What are some means of spore dissemination?
wind, gardening, construction, lawn mower, etc.
37
Hyphae
microscopic, long, branching filaments
38
True or false: hyphae are the same thing as yeasts
False (they are distinct from each other!!)
39
Mycelium
tangled mass of hyphae that can grow to huge proportions
40
Armillaria species (honey fungus) is well known because:
it has grown over 2000 acres underground in Oregon; largest organism on Earth
41
___ are asexual spores
Conidia
42
True or false: fungi are everywhere, and infections are common, but only a very small percentage of all fungi cause human disease
True
43
Yeasts are ____, ___ or ____
unicellular, oval or round
44
2 asexual reproductive modes of yeast
1. cell budding (asymmetrical) | 2. fission (symmetrical)
45
True or false: yeast cells can sometimes form chains, and when this happens, they become multicellular
False - they are still unicellular since there is no connection or cell-to-cell communication between chained cells
46
Yeast sexual form of reproduction is called:
conjugation
47
Yeast asexual forms of reproduction (2)
a and alpha
48
True or false: Yeast life cycle can change how pathogenic they are
True
49
Moulds form ____, which undergo ___ growth
hyphae; apical
50
True or false: all hyphae are septate
false; can be septate or non-septate
51
How many nuclei can molds have in their hyphae?
one or more (uni or multi-nucleate)
52
When moulds branch, they can form what kinds of angles?
Acute + right angles
53
True or false: molds form different types of hyphae
True
54
Characteristics of hyphae (how are they different/distinct)?
1. septate vs aseptate 2. hyaline vs dematiaceous (clear vs pigmented) 3. branching or non-branching 4. angle of branching (acute or not)
55
Fungi can have an organelle called _____ which allows for apical growth of hyphae
Spitzenkorper
56
Vegetative hyphae
form that gathers nutrients
57
aerial hyphae
reproductive form
58
True or false: hyphae can be very distinctive looking and can be diagnostic
True
59
All sexual fungal life cycles consist of _____ and is followed by _____.
plasmogamy; karyogamy
60
True or false: the transition between plasmogamy and karyogamy is usually rapid
False - it can be, or it can take up to years. Depends heavily on the right environmental conditions for karyogamy to follow
61
Molds can have what kind of life cycles?
both sexual and asexual
62
Describe the asexual life cycle of molds
1. conidia (asexual spores) undergo swelling and apical growth to form a germling 2. germling elongates and branches to form hyphae 3. hyphae continue to form and tangles to form mycelium 4. conidiophore can form within mycelium and disperse more conidia thru wind or disruption of soil
63
What are dimorphic fungi?
Fungi that can occur as yeast and mycelial forms
64
Dimorphic fungi are usually ____ dimorphic
thermally
65
Why is it important to study dimorphic fungi?
A lot of them are clinically relevant. Yeast form survives better at body temperature (37ºC)
66
True or false: sexual and asexual stages of same fungus have different names
True
67
Name commonly used for naming the species of fungus for clinical purposes
Anamorph (according to asexual reprod.)
68
____ ____ are often critical diagnostic importance
Asexual structures
69
Most human pathogenic fungi produce _____ ____ as the reproductive and infectious propagule
asexual conidia
70
Major fungal phyla were traditionally based on ____ ____ ____. Now, it's mainly ___.
sexual reproductive structures; genetics
71
Three major fungal phyla:
1. Ascomycetes 2. Basidiomycetes 3. Zygomycetes (group that contains mucormycota)
72
Ascomycetes
8 sexual spores inside ascus
73
Basidiomycetes
4 sexual spores externally on basidium
74
Basidium
little pedestal
75
Ascus
sac
76
True or false: basidiospores, ascospores, and zygospores are sexual propagules and do meiosis
True
77
Zygospore arises from ___ ___ and are ____
sexual conjugation; diploid
78
Conidiophore arises from ____
hyphae
79
Blastic conidia
parent cell enlarges first and then conidium is visible before the septum is laid down to separate parent and daughter cell
80
Thallic conidia
Septum is formed before differentiation into conidium occurs
81
Arthroconidia
Septa are laid down, become conidia, and then fragment into individualized cells
82
_-___ is often targeted by antifungals in Candida cell wall
Beta-glucan
83
Pathology of fungal cell wall
Can be irritants, can activate complement, immunogenic, allergenic, immunopathogenic, immunomodulatory
84
Pathogenesis of fungal cell wall
Signaling, morphogenesis, pathogenicity are altered in response to the host: can attach to host cells and form biofilms which increases resistance to antifungals
85
Diagnostics of fungal cell wall
staining properties, antigenicity that can indicate the type of fungus causing infection
86
True or false: ascomycetes, deuteromycetes, basidiomycetes, and zygomycetes all have chitin in their fibrillar layer and differ in whether they have glucans in fibrillar or matrix layer
True
87
____ are harder to treat because they lack some common drug targets
Zygomycetes
88
What antifungal targets are particularly sensitive in fungi?
ergosterol, unique polysaccharides like glucans
89
Major classes of antifungal drugs
1. membrane function 2. cell wall synthesis (echinocandins) 3. ergosterol synthesis (azoles + allylamines) 4. nucleic acid synthesis (pyrimidine analog)
90
Amphotericin B is a ____
polyene
91
Amphotericin B is both:
amphoteric and amphipathic
92
Amphotericin B works as an antifungal by:
forming a pore/channel which lyses fungal cell
93
True or false: spectrum of azoles depends greatly on the agent
True
94
Mechanism of azoles:
blocks synthesis of ergosterol in fungal membrane which causes accumulation of toxic sterol precursors in the cytoplasm
95
True or false: with azoles, you have to match the agent to the fungus
True
96
Echinocandins mechanism
non-competitively inhibits beta-1,3-glucan synthase enzyme complex, which prevents resistance against osmotic forces and causes cell lysis
97
Echinocandins spectrum
most yeast species but is not the best choice for Aspergillus (since it's just fungistatic)