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Fungi
& Molds
Fungi Are eukaryotic heterotrophs.
Frequently decomposers, sometimes parasites.
Usual structure is a mass of entangled filaments called Hyphae
Hyphae can have cross walls (Septum) separating individual cells. Or have
no separations.
Overall mass is called mycelium
Mushroom showing mycelium & hyphae
Reproduction
:
- Fungi differ from many organisms in that they:
- Reproduce sexually & asexually
- Longest stage of life cycle is in the haploid (N) stage NOT the diploid (2N) stage.
- Asexual reproduction is accomplished through the creation and spreading of asexual
spores.
- Sexual reproduction is accomplished through creation and spreading of sexual
spores by opposite mating types ((+) & (-)).
Divisions
:
There are 3 major divisions of fungi - Based on Characteristics of sexual spores and
fruiting bodies
Division Zygomycota:
- Example: Black Bread mold
- Hyphae produce Sporangium which form spores asexually which are
released to form new mycelia.
- Reproduce sexually also.
- Hyphae of (+) and (-) mating types called Gametangia fuse to form a
diploid (2N) Zygospore
- Zygospore undergoes meiosis to produce spores which are then released
Life Cycle of Bread Mold
- Sexual reproduction
(see fig. 19-6, pp. 410 in text)
- Hyphae called Stolons of opposite mating types (+ & -) will fuse to
form a structure called Gametangia.
- Diploid (2N) Zygospore is formed.
- Zygospore produces sporandia which undergoes meiosis to release haploid (N) spores.
Division Ascomycetes (Sac Fungi)
- Named because sexual spores are produced in small sacs called asci (ascus).
- Asexual spores are produced on conidia by special hyphae called conidiophores.
Life cycle of an ascomycete
Division Basidomycota:
- Include mushrooms, shelf fungi & puffballs
Examples of division basidomycota
- Name derives from formation of a transient diploid (2N) stage of the life cycle called
the Basidium.
Life cycle of basidiomycota
NOTE: NEVER eat a wild mushroom. Many are extremely toxic and can cause
serious injury or death if eaten.
Ecological Significance
:
- Are valuable decomposers which function to return organic material back to
the ecosystem.
- Fungi can form valuable symbiotic relationships
- Example are lichens which is a symbiotic relationship with algae.
lichens
Have great economic value
Yeast is a unicellular fungus used for baking and brewing.
Many mushrooms are edible
Diseases caused by fungi.
Plants are most vulnerable to molds & fungi.
It is a serious threat to agriculture some common crop diseases caused by molds &
fungi are:
- Potato blight
- Wheat rust
- Corn smut
Can cause disease in humans.
"Athlete's foot"
Ring worm
Thrush and other yeast infections
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Mr. Stanley
Last updated: October 22, 2003