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Mycology and Parasitology > Mycology > Flashcards

Flashcards in Mycology Deck (13)
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1
Q

Fungal relationships

A

Saprobes: organism that lives on dead or decaying material
Commensals: organism that lives with another organism deriving benefits from host, may or may not be beneficial, NOT harmed
Parasites: benefits from the host without contributing to the relationship and is harmful to host

2
Q

Plasmalemma

A

Bilayered of phospholipids and sterols (ergosterol, zymosterol)

Protects cytoplasmic contents, regulates intake and secretion of solutes, facilitates capsule and cell wall synthesis

3
Q

Ergosterol

A

Pharmacological target
Imidazole antifungals inhibit synthesis (more specific)
Polyene antifungals bind more tightly to ergosterol than cholesterol but created more side effects

4
Q

Cell wall

A

Antigenic in nature
Multilayered: polysaccharides (hexose and hexosamine polymers) 90% and proteins and glycoproteins 10%

Provides shape, rigidity, strength, and protection from osmotic shock

5
Q

Major polysaccharides of fungal cell wall

A

Chitin (N-acetyl glucosamine)
Alpha-glucan (D-glucose)
Beta-glucan (D-glucose)
Mann an (D-mannose)

6
Q

Capsule

A

Polysaccharide structure
Antiohagocytic and virulence factor
Not all fungi

Cryptococcus neoformans

7
Q

Yeast

A

Unicellular
Reproduce by nuclear fission or budding
Bud = blastoconidia
Pseudohyphae

8
Q

Mold

A

Multicellular
Hyphae (mycelium)
Spores

9
Q

Hyphae

A

Septate: divided by crosswalls

Coenocytic or nonseptate: multinucleate

10
Q

Mycelium

A

Project above surface (aerial)

Vegetative: growth on or beneath surface

11
Q

Dimorphic

A

Capable of growing in mold or yeast form under different environmental conditions (temp, CO2, nutrients)

Thermal dimorphism
<37C grows as filamentous fungi (mold)
>37C grows as yeast

12
Q

Fungal spores

A

Reproduction: normally haploid, unicellular

Sexual reproduction: involves meiosis, preceded by fusion of protoplasm and nuclei of two compatible mating types, telomorph

Asexual reproduction: involves mitosis, anamorph

13
Q

Laboratory diagnosis

A

Direct microscopic examination
Potassium hydroxide - colorless cells
Calcofluor white - fluorescence
India ink evaluation of CSF - colorless cells with halos (Cryptococcus neoformans)

Culture (slow growing)
Sabouraud dextrose agar on mycobiotic agar
Morphology or PCR

Serology (Ab screening)

Molecular techniques (fungal antigen detection)