§ Fungi are classified according to their structure and method of reproduction.
§ The four main groups are:
1. common mold - Zygomycota
2. sac fungi - Ascomycota
3. club fungi - Basidiomycota
4. imperfecti fungi - Deuteromycota
The Common Molds
§ Phylum Zygomycota are the familiar molds that grow
on meat, cheese and bread
§ Their life cycles include a zygospore.
§ A zygospore is a resting spore that contains zygotes
formed during the sexual phase of the mold's life cycle.
Structure and Function of Bread Mold
§ Rhizopus stolonifer is black bread mold.
§ There are two different kinds of hyphae on bread mold.
1. rhizoids - rootlike hyphae that penetrate the bread's surface
► anchor the fungus to the bread, release digestive enzymes, and absorb digested
stolons - stemlike
hyphae that run along the surface of the bread
► sporangiophores push up from the stolon and form sporangia at their tips
► a single sporangia may contain 40,000 spores
Life Cycle of Molds
§ They have both a sexual and asexual phase.
§ The sexual phase begins when hyphae from different
mating types fuse and produce gametangium ( gamete forming structures)
§ Haploid gametes fuse to produce diploid zygotes.
§ The zygospore develops a thick wall and can remain dormant for a long period of
§ The zygospore germinates and a sporangia emerges.
§ The sporangia reproduces asexually by releasing haploid
spores produced by meiosis.
The Sac Fungi
§ Phylum Ascomycota is named for the ascus, a reproductive
structure that contains spores.
§ It is the largest phylum of the kingdom Fungi.
Life Cycle of Sac Fungi
§ Life cycle includes both asexual and sexual reproduction.
§ In asexual reproduction, tiny spores called conidia,
are formed at the tips of conidiophores (specialized hyphae) which can be released under good conditions
forming haploid mycelium.
§ Sexual reproduction occurs when haploid hyphae of two different mating types grow
§ They produce a fruiting body where sexual reproduction continues.
§ The ascus forms within the fruiting body that contains
two nuclei of different mating types which fuse to form a diploid zygote.
§ Meiosis is follows by mitosis producing ascospores
which under the right conditions germinate and grow into haploid mycelium.
§ Yeasts are unicelluar fungi.
§ Humans use them for baking and brewing.
§ The dry granules contain ascospores, which become active in a moist environment.
§ They reproduce asexually by budding (cell division
in rapidly growing yeast cells)
§ Yeasts use the process of alcoholic fermentation to obtain energy.
§ The byproducts are carbon dioxide and alcohol.
§ The alcohol in bread dough evaporates during baking and the carbon dioxide make
the bread dough rise.
§ These yeasts are called "sugar fungi" due to the fact that they grow in a nutrient
The Club Fungi
§ Phylum Basidiomycota or club fungi gets its name from
a specialized reproductive structure that resembles a club.
§ Basidium is the spore-bearing structure.
§ Basidia are found on the gills on the underside of mushroom caps.
Life Cycle of Club Fungi
§ It is the most elaborate life cycle of all the fungi.
§ A basidiospore germinates to produce a haploid primary mycelium, which begins
§ Mycelia of different mating types fuse to produce a secondary mycelium.
§ Secondary mycelia might grow in the soil for years reaching an enormous size making
them the largest organism in the world.
§ When conditions are right, fruiting bodies (mushrooms) push above the ground.
§ The fruiting bodies expand with great speed and may appear overnight.
§ This is caused by cell enlargement NOT cell division.
§ The hyphae enlarge rapidly by taking in water.
§ The mushroom cap exposes hundreds of gills lined with basidia.
§ Basidiospores form at the edge of each
basidium and are ready to be scattered.
§ A single mushroom can produce billions of spores, and giant puff balls can produce
Diversity of Club Fungi
§ Basidiomycetes include:
► Shelf fungi
► Jelly fungi
► Rusts (plant parasites)
Edible and Inedible Mushrooms
§ Many types of mushrooms have been considered delicacies.
§ Some types are cultivated for food such as the mushrooms on your pizza, portobello
mushrooms on your filet and shiitake mushrooms.
§ Wild mushrooms are a different story.
§ The result of eating a poisonous mushroom can be severe illness, or even death.
The Imperfecti Fungi
§ Phylum Deuteromycota is an extremely varies phylum.
§ It is composed of fungi that do not fit into any other phylum because they do
not have a sexual phase in their life cycle.
§ They resemble ascomycetes or basidiomycetes or even zygomycetes.
§ The term imperfecti refers to fungi that DO NOT appear
to have sexual reproduction.
§ Penicillium is one of the best known imperfecti fungi.
§ This mold grows on fruit and is the source of the antibiotic penicillin.
§ Penicillium reproduces asexually by means of conidia, so it may have evolved from an ascomycete that lost the
sexual phase of its life cycle.