IB. Medical Mycology | 22. Characterization and classification of human pathogenic fungi. Flashcards

1
Q

I. Characterization of human pathogenic fungi
1. Are fungi eukaryotes or prokaryotes?

A

They are Eukaryotes

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2
Q

I. Characterization of human pathogenic fungi
2. Which organelles does each fungal cell have?

A
  • nucleus and nuclear membrane
  • endoplasmic reticulum
  • mitochondria
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3
Q

I. Characterization of human pathogenic fungi
3. What types of aerobes are fungi?

A

most fungi are obligate or facultative aerobes

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4
Q

I. Characterization of human pathogenic fungi
4. Are fungi exogenous or endogenous?

A

most pathogenic fungi are exogenous
- their natural habitats being water, soil, and organic debris

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5
Q

I. Characterization of human pathogenic fungi
5A. What are the forms that fungi can grow in?

A
  1. Yeast
  2. Mould
  3. Dimorphic
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6
Q

I. Characterization of human pathogenic fungi
5B. What are the features of “YEAST” form of fungi?

A
  • unicellular growth pattern
  • can be spherical or ellipsoidal
  • they reproduce by budding
  • when the buds are not able to separate -> pseudohyphae
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7
Q

I. Characterization of human pathogenic fungi
5C1. What are the features of “Mould (Mycelia)” form of fungi?

A

Produces multicellular filamentous colonies which contains the following:
- Hyphae
- Mycelium

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8
Q

I. Characterization of human pathogenic fungi
5C2. Mould (Mycelia) produces multicellular filamentous colonies which contains Hyphae
=> What are the features of Hyphae?

A

Hyphae - cylindrical tubules composed of fungal cells attached end to end
- Vegetative hyphae – penetrates the supporting medium and absorb nutrients
- Aerial hyphae – project above the surface of the mycelium and bear the reproductive structures of the mould

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9
Q

I. Characterization of human pathogenic fungi
5C3. Mould (Mycelia) produces multicellular filamentous colonies which contains Mycelium
=> What are the features of Mycelium?

A

the collective term for a mass of hyphae

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10
Q

I. Characterization of human pathogenic fungi
6. What are the features of “Dimorphic” form of fungi?

A
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11
Q

I. Characterization of human pathogenic fungi
7A. What are the cell features of fungal cells?

A
  1. Cell wall
  2. Nucleus
  3. Cytosol complex
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12
Q

I. Characterization of human pathogenic fungi
7B. What are the features of cell wall in fungi?

A
  • multi-layered
  • composed of carbohydrates, polysaccharides and some proteins (chitin, glucans, mannans, glucomannans, galactomannans)
  • some are capsulated (Cryptococcus neophormans – stained by indian ink)
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13
Q

I. Characterization of human pathogenic fungi
7C. What are the features of cell membrane in fungi?

A
  • bilayer
  • composed of glycoproteins, lipids, and ergosterol (sterol)
  • differs from mammalian cell membranes, which contain cholesterol
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14
Q

I. Characterization of human pathogenic fungi
7C. What are the features of cell wall in fungi?

A
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15
Q

I. Characterization of human pathogenic fungi
7D. What are the features of cell nucleus in fungi?

A
  • Membrane-bound (eukaryotic)
  • Multichromosomal and can be haploid or diploid
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16
Q

I. Characterization of human pathogenic fungi
7E. What are the features of cytosol complex in fungi?

A
  • contains several organelles
  • nucleus, mitochondria, Golgi apparatus, ribosomes, a well-defined endoplasmic reticulum and other inclusions
17
Q

I. Characterization of human pathogenic fungi
8. What are the shape of size of fungal cells?

A
18
Q

I. Characterization of human pathogenic fungi
9. Explain metabolism by fungi

A
  • exclusively heterotrophic
  • produces various metabolites - primary (e.g. citric acid, ethanol) and secondary (e.g. alpha amanitin, aflatoxin)
  • doubling time is long (hours) compared with most bacteria (minutes)
19
Q

I. Characterization of human pathogenic fungi
10. What are the staining properties of fungi?

A
  • false Gram-positive
  • can be stained by
    +) methenamine-silver
    +) periodic acid Schiff-stain (PAS
20
Q

I. Characterization of human pathogenic fungi
12A. What are the asexual spores?

A
  1. Conidia
    - non-sexual bud produces from transformation of vegetative yeast or hyphal cell
  2. Blastospore
    - conidial formation through a budding process (yeast)
  3. Arthrospore
    - type of segmented spore.
    - Very light => carried easily by air
  4. Chlamydospore
    - large thick wall produced from terminal or intracalary hyphal cells
  5. Sporangiospore
    - spore formed within a sac
21
Q

I. Characterization of human pathogenic fungi
11A. What are the features of Reproduction of the human pathogenic fungi?

A
  • Fungi can produce spores to enhance their survival
  • Spores can dispersed, they are more resistant and can germinate
  • The spores can be used for both asexual and sexual reproduction
22
Q

I. Characterization of human pathogenic fungi - Asexual reproduction
12B. How does conidia reproduce?

A
  • non-sexual bud produces from transformation of vegetative yeast or hyphal cell
23
Q

I. Characterization of human pathogenic fungi - Asexual reproduction
12C. How does Blastospore reproduce?

A

Blastospore
- conidial formation through a budding process (yeast)

24
Q

I. Characterization of human pathogenic fungi - Asexual reproduction
12D. How does Arthrospore reproduce?

A

Arthrospore
- type of segmented spore.
- Very light => carried easily by air

25
Q

I. Characterization of human pathogenic fungi - Asexual reproduction
12E. How does Chlamydospore reproduce?

A

Chlamydospore
- large thick wall produced from terminal or intracalary hyphal cells

26
Q

I. Characterization of human pathogenic fungi - Asexual reproduction
12E. How does Sporangiospore reproduce?

A

Sporangiospore
- spore formed within a sac

27
Q

I. Characterization of human pathogenic fungi
13A. What are the features of sexual reproduction by fungi?

A
  1. Sexual spores are products of meiosis
  2. Sexual spores:
    - Ascospore (Pneumocystis, Candida)
    - Basidiospore (Cryptococcus, Malassezia, Trichosporon)
    - Zygospore (Mucor, Rhizopus)
28
Q

I. Characterization of human pathogenic fungi - sexual reproduction by fungi
13B. How does Ascospore (Pneumocystis, Candida) reproduce?

A

a spore formed within an ascus (a sac like)

29
Q

I. Characterization of human pathogenic fungi - sexual reproduction by fungi
13C. How does Basidiospore (Cryptococcus, Malassezia, Trichosporon) reproduce

A

a spore formed on basidia

30
Q

I. Characterization of human pathogenic fungi - sexual reproduction by fungi
13D. What are the features of Zygospore (Mucor, Rhizopus)?

A

Deuteromycotina – fungi imperfecti

(Deuteromycetes are called imperfect fungi because only their vegetative and asexual phases are known. When their sexual phases were known, they were moved to a different class - ascomycetes and basidiomycetes)

31
Q

II. Classification based on growth/morphology
1. Give the Classification based on growth/morphology?

A
32
Q

II. Classification based on growth/morphology
2. What are the features of Yeast/ unicellular?

A

a) Unicellular growth pattern
b) Spherical or ellipsoidal
c) Reproduce by budding

33
Q

II. Classification based on growth/morphology
3. What are the features of Mould (multicellular)?

A

Mould (multicellular)
a) Septate Hyphae: cross wall divide into uninucleate unit i)
- Produces multicellular filamentous colonies
b) Non-Septate Hyphae: no cross wall

34
Q

II. Classification based on growth/morphology
4. What are the features of Dimorphic (multicellular)?

A

a) Can change to grow either yeast(unicellular) or mold(multicellular)

b) Depends on environmental conditions and temperature (body temp= yeast, lower temp=
mould)

c) Cultivation temperature of fungi to detect dimorphism is 25 degrees and 37 degrees

d) Ie; candida albicans, sporothrix, Coccidioides immitis