Mycology: General Characteristics and Reproduction

Vocabulary flashcards covering key mycology terms and concepts from the lecture notes.

Mycology

The science dealing with fungi; derived from Greek mykes meaning mushroom.

Fungi

Eukaryotic organisms classified in their own kingdom FUNGI; include molds and yeasts; heterotrophic; cell walls contain chitin; ergosterol in cell membranes.

Yeast

Unicellular, spherical/ellipsoidal fungi; reproduce by budding or fission; form creamy colonies; tissue form at 37°C.

Mold

Multicellular, filamentous fungi that grow as hyphae forming a mycelium; typically produce cottony colonies.

Saprobe

Organism obtaining nutrients from decaying organic matter; many fungi are saprobes.

Thallophyte

Organisms with a simple plant-like body lacking true roots and stems; fungi historically classified as thallophytes.

Chitin

Major component of fungal cell walls; polymer of N-acetylglucosamine.

Ergosterol

Sterol in fungal cell membranes; target of many antifungal drugs.

Spores

Reproductive units produced sexually or asexually; highly resistant.

Asexual reproduction

Reproduction without fusion of genetic material; spores formed asexually.

Sexual reproduction

Reproduction involving meiosis and fertilization; sexual spores formed; genetic recombination occurs.

Perfect fungi (teleomorph)

Fungi that have a sexual stage.

Imperfect fungi (anamorph)

Fungi that do not exhibit a sexual stage (in lab or naturally); many clinically important.

Dimorphism

Ability of some fungi to exist in two forms depending on growth conditions (mold vs. yeast).

Thermally dimorphic

Dimorphism controlled by temperature; mold at 25–30°C; yeast at 35–37°C.

Histoplasma capsulatum

Dimorphic fungus causing histoplasmosis; one of the medically important dimorphic fungi.

Sporothrix schenckii

Dimorphic fungus causing sporotrichosis; commonly presents as a subcutaneous infection.

Paracoccidioides brasiliensis

Dimorphic fungus causing paracoccidioidomycosis; known for multiple budding.

Blastomyces dermatitidis

Dimorphic fungus causing blastomycosis; broad-based budding yeast at body temperature.

Talaromyces marneffei

Dimorphic fungus causing talaromycosis; shows yeast form at 37°C in tissues.

Cryptococcus neoformans capsule

Encapsulated yeast with antiphagocytic capsule; virulence factor.

Antiphagocytic capsule

Capsule that helps fungi evade phagocytosis by immune cells.

Gram stain (fungi)

Fungi are generally Gram-positive; staining helpful for identification, with limitations.

Periodic acid–Schiff (PAS)

Stain highlighting fungal cell wall carbohydrates; fungi stain bright red.

Grocott’s methenamine silver (GMS)

Silver stain used to visualize fungi in tissues.

Calcofluor white

Fluorescent stain binding to fungal cell walls; appears apple green under fluorescence.

Lactophenol cotton blue

Staining medium used to visualize fungi; contains lactic acid, phenol, glycerine, blue dye.

Hyphae

Thread-like filaments that form the fungal body; can be septate or aseptate.

Septate

Hyphae divided by cross-walls into separate cells.

Aseptate / Coenocytic

Hyphae without septa; multinucleate, continuous cytoplasm.

Dematiaceous

Darkly pigmented hyphae due to melanin in the cell wall.

Hyaline

Colorless or lightly pigmented hyphae.

Mycelium

Intertwining network of hyphae; comprises vegetative and aerial parts; aerial hyphae bear spores.

Conidia

Asexual spores produced by conidiophores.

Macroconidia

Large, multicellular conidia (often with distinctive shapes).

Microconidia

Small, unicellular conidia.

Blastoconidia

Bud-like conidia produced by budding yeasts.

Chlamydoconidia

Thick-walled resting spores formed by enlargement of terminal hyphal cells.

Arthroconidia

Conidia formed by fragmentation of septate hyphae; also called arthrospores.

Sporangiospores

Spores contained in a sporangium produced on a sporangophore; characteristic of Zygomycetes.

Zygomycetes

Fungi producing sporangia; include Rhizopus, Absidia, Mucor.