jimtrue.com : school : BSC2011L : Lab 03: Kingdom Fungi

Posted by Jim True on September 14, 2004 2:24 PM. Last Updated October 22, 2006 9:23 PM

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Lab 03: Kingdom Fungi

Objectives

Know the basic characteristics for the slime molds (Kingdom Protista)
To learn the basic characteristics for the Kingdom Fungi
To learn the structural difference between each of the four divisions of fungi.
To learn the reproductive structures and cycles of the four divisions of fungi.

Terms to Know:

saprobe: organism that secretes enzymes outside itself to break down organic material and then absorbs the nutrients released.
spore: enclosing structure
fruiting body
mycorrhiza
sporangium(-a): asexual fruiting body for
hypha(e)
mycelium
septa
coenocytic
septate
lichen
plasmodium
pseudo-plasmodium

Kingdom Fungi

(few)Uni-/(most)Multicellular, eukaryotes, saprobic organisms. All heterotrophs.
Saprobes - secrete digestive enzymes, then absorb digested nutrients.
Basic Fungal "body" (except for unicellular yeasts) is filamentous thread-like structure- Hyphum (singular threadlike structure). Typically (except when they germinate) multiple hyphae form a mass, mycelium
Hyphae may have internal cross walls (septate) or none (aseptate ("lacking septate"), a.k.a. coenocytic "common cell")
Fungal cells in hyphae are typically HAPLOID (n)! Asexual reproduction occurs by mitosis producing spores in an asexual Sporangium (a.k.a. fruiting body) or Conidiophore bearing spores called conidia.
Sexual reproduction involves sexual sporangia in which cellular fusion (haploid fuse to diploid), meiosis (diploid to haploid) and mitosis occur. Sexual structures are of taxnomic significance:
- P.Zycomycota - 1 sexual zygospore suspended between 2 special hypae. Always aseptate, except in sexual zygospore. (Zygos - 'yolk') Only location septae ever found , eg. Rhizopus, known as the black bread mold.
- P.Ascomycota - 8n ascopores produced inside each saclike Ascus ("sack or bag"), e.g. Peziza, morrels, truffles, and some kinds of molds. Yeasts are ascomycetes; unicellular fungi. Creates buds (mitotically); sexually they can fuse a haploid cell.
- P. Basidiomycota - 4n basidiospores produced on outside of each stalklike Basidium, e.g. Coprinus.
- (P. Deuteromycota) - No sexual stage, only asexual via conidiophores, eg. some Penicillium.
- Lichen - fungus in a symbiotic relationship with cyanobacteria. Colonizing organisms; usually found where nothing else can live or grow.

Fungus-like Protista (Slime molds)

Usually very wet environments. Slime molds. 2 phyla have 2 stages in the life cycle:

Vegetative - ("to feed") Feeding stage - P.Myxogastrida form a plasmodium, weblike unicellular body form. Genus Physarum, yellow plasmodium (can watch the cytoplasm moving through the web). P.Dictyostelida (cellular slime molds), feeding stage is individual ameboid cells.
Reproductive Stage - (for many organisms, reproduction occurs when things get bad, moisture levels begin to drop, or food begins to disappear). Myxogastrids - Sporangia extend from the plasmodium. Dictyostelids, ameboid cells cluster together to form a pseudo-plasmodium and from this a sporangium arises.

Myxogastrida -
Dictyostelida -

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