Fungi Characteristics, Reproduction, and Lichen Symbiosis

Fungi

Over 100,000 species; many species cause disease in humans, animals, and plants; many species are beneficial.

Decompose dead plants

Fungi recycle elements.

Mycorrhizae

Form symbiotic relationships with plants and help absorb water and nutrients.

Role of fungi

In food and antibiotic production.

Cell Type of Fungi

Eukaryotic.

Cell Membrane of Fungi

Sterols present.

Cell Wall of Fungi

Glucans; mannans; chitin (no peptidoglycan).

Spores in Fungi

Sexual and asexual reproductive spores.

Metabolism of Fungi

Limited to heterotrophic; aerobic, facultatively anaerobic.

Molds and fleshy fungi

The fungal thallus (body) consists of hyphae filaments; a mass of hyphae

Vegetative hyphae

Obtain nutrients while aerial hyphae are involved with reproduction.

Yeasts

Nonfilamentous and unicellular.

Budding yeasts

Divide unevenly.

Fission yeasts

Divide evenly.

Dimorphic fungi

Yeastlike at 37C and moldlike at 25C.

Asexual spores

Produced via mitosis and cell division; formed by the hyphae of one organism.

Plasmogamy

Haploid donor cell nucleus (+) penetrates cytoplasm of recipient cell.

Karyogamy

+ and nuclei fuse and form diploid zygote.

Meiosis

Diploid nucleus produces haploid nuclei (sexual spores).

Mycosis

Fungal infection.

Systemic mycoses

Deep within the body, affect a number of tissues and organs.

Subcutaneous mycoses

Beneath the skin.

Cutaneous mycoses

Affect hair, skin, and nails; also known as dermatomycoses.

Superficial mycoses

Localized (e.g., hair shafts).

Opportunistic mycoses

Fungi harmless in normal habitat but pathogenic in a compromised host.

Aspergillus niger

Production of citric acid.

Saccharomyces cerevisiae

Bread, wine, hepatitis B vaccine.

Mutualistic combination in lichens

A green alga (or cyanobacterium) and fungus.

Three morphologic categories of lichens

Crustose—encrusted on the substratum; Foliose—leaflike; Fruticose—fingerlike.