Kingdom Fungi Notes

Mycology – study of fungi

Domain Eukarya

Kingdom Fungi

            Absorptive heterotrophs

            Eukaryotes

            Classified by type of fruiting body and spore formation

            Dominant body form haploid

            Most multicellular

I.                    Phylum Oomycota – water mold

Cell wall:  cellulose – often placed in Kingdom Protista

Fact to remember:  caused Irish Potato Famine

Asexual reproduction:  zoospores

Sexual reproduction:  egg and sperm

II.                 Phylum Zygomycota

Cell wall:  chitin

Sexual reproduction:  conjugation forms zygospores

Asexual reproduction:  haploid spores

Example:  black bread mold

III.               Phylum Ascomycota – sac fungi

Largest fungal phylum

Asexual reproduction:  conidia

Sexual reproduction:  ascospores

Examples:  truffles, morels, yeast

Facts to remember:  yeasts are unicellular

Pigs are used to locate truffles

Ascomycetes are used to study crossing-over because of the arrangement of the eight ascospores in the ascus

IV.              Phylum Basidiomycota – club fungi

Examples:  mushrooms, puffballs, toadstools, bracket fungi

V.                 Phylum Deuteromycota – Fungi Imperfecti

Imperfect fungi

No known sexual reproduction

Example:  Penicillium grows on fruit, produces the antibiotic penicillin, reproduces asexually by conidia

Other examples:  ringworm, athlete’s foot, black spot on roses, and tomato blights

Compare and Contrast Fungi with other Eukaryotic Organisms

Fungi are heterotrophs like animals and some protists, but unlike animals they are absorptive heterotrophs.  Plants and some protists are autotrophs, fungi are heterotrophs.  Like some animals and some protists some fungi are parasites.  Most fungi are saprophytes.  Like plants, fungi have cell walls.  Unlike plants the cell wall of fungi contains chitin not cellulose.  Chitin is found in the exoskeleton of arthropod animals.  Fungi store food like animals in the form of glycogen.  Like plants fungi are sessile, which is unlike most animals and protists.  Like primitive plants the dominant body form of fungi is haploid.  The dominant body form in advanced plants and animals is diploid.

Medical and Economic Importance of Fungi

Most fungi are decomposers, recycling nutrients in the environment.  They also function in food production.  Yeast is used to make bread rise and many fungi are used to make cheese.  Many fungi are used as food.  Truffles and morels are considered delicacies.   A fungus is the source of the antibiotic penicillin.  Fungi have a symbiotic relationship with green algae and cyanobacteria to form lichen.  Lichens are pioneer organisms.  They are the first organisms to move into an area because they are able to form soil.  Fungi also have a symbiotic relationship with some plants by forming mycorrhizae.  Mycorrhizae help plants absorb water, nutrients, and minerals and the plant provides the fungi with food.  Orchids are dependent on fungi for seed germination.

Yeasts are used in genetic engineering similar to how E. coli is used.

Some fungi are harmful.  Some mushrooms are deadly.  Fungi cause bread to mold. Fungi are the source of many plant diseases, such as wheat rust, corn smut, mildews, chestnut blight, and Dutch elm disease.  Ergotism may be what led to the Salem witches.  Ergot is an ascomycete that infects rye plants.  It has been used to make LSD and also to treat high blood pressure and bleeding after childbirth.   Fungi may cause 50% of plant diseases in the tropics because of the humid climate. 

Human fungal diseases include athlete’s foot, ring worm, and yeast infections.  Some mushrooms are deadly to people.  Other animals are also affected by fungi.  A fungus may be the cause of the decline of amphibians.