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Chapter 12 - Fungi
Transcript of Chapter 12 - Fungi
Reproduction in Black Bread Mold
12B - Characteristics of Fungi
Destructive fungi costs millions of dollars to deal with, either in terms of property or crop damage
12.1 - Destructive Fungi
The fungus portion forms a dense web of hyphae for algae/cyanobacteria to grow.
Receives organic nutrients, such as sugars and amino acids, from the plant.
May also helps ay help maintain water in the soil around the plant.
Hyphae also absorb and release phosphorus, copper, and other minerals into the roots from the soil.
The hyphae grow around or into (harmlessly) into the plant's roots, increasing the absorptive surface of the plant’s roots, and resulting in more nutrients entering the plant.
(usually basidiomycotes) lives symbiotically with a plant.
Mutualism: Mycorrhizae and Lichens
Mushrooms, puffballs, stinkhorns, rusts, smuts, and earth stars, and shelf fungi
12.8 - Phylum Basidiomycota
Called sac fungi because of tiny saclike structures ascus (plural asci), in which the sexual spores (ascospores) develop.
12.7 - Phylum Ascomycotes
12.5 - Reproduction of Fungi
12C - Classification of Fungi
12.4 - Colonial Structure of Fungi
What do St. Anthony's fire in the Middle Ages, Peter the Great, childbirth, LSD, and headaches have in common?
12A - Fungi and Man
Study of fungi is mycology
There are about 16,000 species of lichens.
The fungus provides water and minerals absorbed from rain/air, and protects it from environmental changes.
Algae/cyanobacteria provides the food for both organisms.
Lichens need only light, air, and minerals to grow.
12.3 Nutrition and Respiration of Fungi
Lady slipper orchid
Some are parasitic, such as the fungi that cause Dutch Elm disease in plants
12.6 - Phylum Zygomycota
Bleeding tooth fungus
Pioneer species worldwide
Indicators of pollution levels.
Ergot rye - fungus on rye that causes hallucinations, burning sensations, paralysis, as well as treating migraines and stimulating contractions in childbirth
Others are pathogenic to humans, such as ringworm, athlete's foot, and thrush
12.2 - Beneficial Fungi
Mushrooms on pizza and cheeses are beneficial fungi used for food, as are truffles (an expensive delicacy ranging from $300-600 up to $1,000-$2000 a pound!)
Penicillin notatum creates a substance that destroys bacteria; we call it penicillin (antibiotic)
Fungi are important decomposers that help plants
Mycorrhizae are fungi that live in a symbiotic relationship with certain plants to enhance absorption of nutrients in the roots; if these fungi are gone, the plants will not survive
The fungal cell walls contain chitin, a complex polysaccharide; they do not contain cellulose like plants.
Fungi are mostly multicellular; yeast is unicellular
Do not have chlorophyll; cannot produce their own food--nonphotosynthetic heterotrophs.
The bodies of fungi are made of masses of filaments woven together; there is no tissue differentiation
Lack chlorophyll; heterotrophic
Some saprophytic, others parasitic; few are both, like
it changes form depending on its environment--dimorphism
Lack specialized organelles for digestion; most have external digestion, secreting enzymes (often from parasitic or poisonous fungi) that digest food externally, which is later absorbed
Most require oxygen for metabolism, but some can grow without
All require abundant moisture, but some can withstand dry conditions
Basic structural units are threadlike filaments called hyphae, which develop from spores.
In some, hyphae are divided into individual cells by cell walls called septa (sing., septum) that usually have pores to allow cytoplasm to travel; some have hyphae that lack septa (nonseptate) which are typically multinucleated
Masses of intertwined hyphae are mycelia (sing., mycelium); they are visible without magnification
Hyphae are grouped according to shape or function:
Rhizoids - hyphae embedded in the material on which the fungus is growing. They support the fungus and secrete enzymes to digest food
Haustoria - hyphae of parasitic fungi that perforate a host’s cells and obtain nutrition directly from the cytoplasm
Aerial hyphae - not embedded in the medium which the fungus is growing; absorb oxygen, produce spores, and spread the fungus.
Sporophores - aerial hyphae that produce spores.
Stolons - -aerial hyphae that connect groups of hyphae together
Most common type is asexual reproduction, when environmental conditions are favorable;; yeast bud by pinching off cells to make more yeast cells
Fungi can also reproduce asexually by fragmentation of the hyphae or mycelia; most common method of asexual reproduction is by spore production.
Sporophores function in the asexual production of spores; it can either be in an enclosure or sac (sporangiophore), formed in a sporangium; if the spores are not in an enclosure, it's a conidiophorec, producing conidia
Sexual reproduction occurs during times of unfavorable environmental conditions; does not occur in all fungi
No male or female fungi, only "plus" (+) and "minus" (-) mating types
Occurs when the hyphae of different mating types come into contact; fused hyphae produce a specialized structure called the fruiting body that forms and releases the spores.
Kingdom Fungi contains over 100,000 species of colonial and unicellular heterotrophic organisms
Fungi are traditionally grouped into phyla based on their colonial structure and method of sexual reproduction.
Usually divided into three phyla—Zygomycota, Ascomycota, and Basidiomycota
Primarily land dwellers. Name derived from the thick-walled sexual structures called zygosporangia (sing., zygospo-rangium) that characterize the members of this phylum.
Genus Rhizopus contains a common food mold - black bread mold (R. nigricans or R. stolonifer).
In asexual reproduction, airborne spores from the sporangia, land in a favorable environment and germinate, forming a small hypha.
Hypha grows into a mycelium with rhizoids, stolons, and finally, sporangiophores and sporangia (either black or shades of brown/green)
Sexual reproduction occurs when hyphae of different mating types touch and form a zygosporangium; when environmental conditions are favorable, the zygotes undergo meiosis and germinate; newly formed hyphae grow into stolons and sporangia, completing the life cycle.
1. Sexual reproduction: Two hyphae from different mating types grow until they touch each other. Nuclei in the tip of each hypha divide several times.
2. The hyphae fuse at the point where they touch.
3. A zygosporangium forms at the point where the hyphae fused. The nuclei of opposite mating types pair, forming diploid zygotes (2n). The zygosporangium forms a thick outer covering and enters a dormant state.
4. Asexual reproduction: When environ- mental conditions are favorable, the zygotes in the zygosporangium undergo meiosis and germinate, forming new hyphae.
5. As the hyphae grow, sporangiophores are formed and new spores are released.
Asexually, conidia (spores) are produced at tip of aerial hyphae in conidiophores; air currents carry the spores away, where they germinate and form new hyphae and mycelia.
Penicillium is a common ascomycetes; they form green spores with surrounding white rings that are visible on oranges and on other food-stuffs.
Other species in this genus produce the flavors of Roquefort (blue cheese), Camembert, and other cheeses; other members include powdery mildews and cup fungi
Yeast are most economically important ascomycotes.
Other used in baking; they produce CO2 that causes bread dough to rise and have light, airy texture.
Important tools for genetics research; have large chromosomes and multiply rapidly; used to help produce Hepatitis B vaccine.
Unicellular sac fungi usually reproduce by budding
Anaerobes and ferment sugars; produce CO2 and ethyl alcohol.
They produce alcohol, they are used to make wine and beer.
Called club fungi because of their basidium that produce basidiospores
Mushrooms are usually saprophytic.
The cap (short-lived) and stipe (stalk) are only the visible fruiting body of an extensive underground network of septate hyphae
Underneath the cap are gills with thousands of basidia, each producing four basidiospores; they are released and fall between the gills onto the soil or carried away by wind and water
Shelf fungi are saprophytes of deadwood or parasites of living trees
Shelf fungi produce spores in pores on the underside of the shelf, which fall out when released and are carried away by wind
The Imperfect Fungi (aka Deuteromycota)
No known sexual stage in their life cycle (or not discovered at this time)
Athlete's foot and thrush (candidiasis) are examples of organisms in this group