What Are Fungi?

§    Fungi are eukaryotic heterotrophs that have cell walls.

§    Chitin, a complex carbohydrate, makes up their cell walls

§    Digest their food outside their bodies and then absorb it

§    Feed on decaying matter in the soil

§    Live as parasites, absorbing nutrients from their host

Structure and Function of Fungi

§    All fungi are multicellular except yeasts.

§    Composed o f thin fi laments called hyphae

§    Cross walls divide some fungi into cells containing one or two nuclei

§    Cross walls are tiny openings through which the cytoplasm and nuclei can move

§    Mycelium is a tangled mass of hyphae

§    Mycelium absorb food due to its large surface area coming into contact with a food source

§    Fruitinq body is a reproductive structure growing from the mycelium in the Sofl beneath it.

§    Clusters of mushrooms are often part of the same mycelium hence, the same organism.

§    A "fairy ring" is composed of the fruiting bodies of mushrooms that developed at the outer edges of a single mycelium.

§    As the center nutrients become depleted, new mushrooms sprout only at the edges of the mycelium producing a ring.

Reproduction in Fungi

§    Most fungi reproduce sexually and asexually.

Asexual Reproduction

§    Cells or hyphae break off from a fungus and begin to grow on their own.

§    Some produce spores which scatter and produce new organisms (a spore is a reproductive cell)

§    Spores are produced in sporangia

§    Sporangia are found at the tips of specialized hyphae called sporangiophores

Sexual Reproduction

§    Involves two different mating types

§    Not male and female but "+" (plus) and "-" (minus)

§    When opposite mating types meet, they fuse, bringing plus and minus together in the same cell.

§    Form a diploid zygote nucleus, which enter meiosis producing haploid spores.

How Fungi Spread

§    Fungal spores are found in almost every environment.

§    Mold will appear where there is the right combination of moisture and food

§    A few liters of fresh air may contain hundreds of spores from many species of fungi

§    Spores will grow if they have the right temperature, moisture and food

§    Some fungi are specialized to lure animals, which disperse fungal spores over a long distance.

§    Stinkhorns smell like rotting meat and attract flies

§    The spore-containing fluid in ingested by the flies that distribute it over many miles.