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13 terms

Test2 lec2 [Fungal Identification]

STUDY
PLAY
Fungi
Eukaryotes
Chemoheterotrophs: organic compounds
Sterols present in membrane
No peptidoglycan in cell wall
Saprophytes
100,000 species (100 are pathogenic)
Mycology: Study of fungi
Molds
Yeasts
Molds
Thallus (body)
Hyphae (filaments)
- Septate (septa or crosswalls)
- Coenocytic (nonseptate) (no septa)

Mycelium (filamentous mass of hyphae)
- vegetative (nutrients)
- aerial (reproduction)
Yeasts
Nonfilamentous
Unicellular
Spherical or oval
Reproduce by budding
Dimorphism
Fungi exhibit two forms of growth
-- 37C: grow as yeast
-- 25C: grow as mold
Life Cycle of Fungi: Spores from Aerial Mycelia
Asexual Spores
- One organism
- genetically identical to parent
- Sporangiospore (in a sac) (sporangium-sac)
- Conidia: not enclosed in sac

Sexual spores
- Fusion of nuclei from 2 opposite mating strains
Nutritional Adaptations of Fungi
Grow in pH of 5.0
Molds: aerobic
Yeasts: facultative anaerobes
Grow in high sugar or salt, low moisture
Require less nitrogen
Metabolize complex carbohydrate
Fungal Diseases
Mycosis: fungal infection
Usually chronic (grow slowly) infection
Five groups based on degree of tissue involvement and mode of entry into body
systemic, subcutaneous, cutaneous, superficial, and opportunistic
Systemic Mycoses
Deep within the body
Affect number of tissues and organs
Caused by saprophytic fungi that live in soil
Route of transmission: inhalation of spores
Histoplasmosis (Histoplasma capsulatum)
Coccidioidomycosis (Coccidioides immitis)
Subcutaneous mycoses
Beneath the skin
Caused by saprophytic fungi that live in soil and on vegetation
Route of transmission: Direct implantation of spores in puncture wound
Sporothrix schenckii : gardeners
Cutaneous Mycoses (Dermatomycoses)
Caused by dermatophytes (fungi that infect only skin, nails and hair)
Secrete keratinase
Route of transmission: direct contact
- human to human
- contact with infected hairs and epidermal cell
Trichophyton, Epidermophyton, Microsporum
Opportunistic mycoses
Generally harmless in normal habitat
Become pathogenic in host who is immunocompromised
Mucormycosis: Rhizopus and Mucor
Aspergillosis: Aspergillus
- lung infections
Candidiasis: Candida albicans
- yeast infection, oral thrush
mycosis
fungal infection
Coenocytic
no septa