| How do fungal feeding hyphae vary among fungi? | Some attach to substrate through specialized hyphae called rhizoids, Parasitic have similar modified hyphae called haustoria that directly absorb food from host cell (tissues) |
| Talk about Ascomycetes. | Sometimes referred to as sac fungi because their spores (Ascospores) are produced in little sacs called asci,
asci are always the terminal cells of special hyphae.
They are usually located in reproductive structure called ascocarp (carpophore)
The end cells (asci) of the ascus bearing hyphae ,in many forms, line the inner surface of the ascocarp, this surface layer is called hymenium or fertile layer. Sterile cells, called paraphyses also arise in the hymenium and are more numerous than asci
Hymenial layer is more or less surrounded by the vegetative haploid hyphae that form a layer called peridium.
The mycelium is composed of segmented and perforated hyphae, which allows the cytoplasm to switch from one cell to another Ascomycetes are terrestrial or aquatic which are saprophytes.
Many sexually reproducing yeasts are Ascomycetes ( edible morels, truffles, red brown and blue green ones degrade food, some cause plant diseases other are important economically. |
| What is the main source of carbon for fungi? | Heterotrophs (Lack chlorophyll), use organic matter as carbon source and feed by absorption by secreting digestive enzymes, these enzymes break down large food molecules into soluble molecules that diffuse through their cell wall, they may be saprophytic, symbiotic or parasitic. |
| Talk about saprophytic fungi. | They are decomposers that feed on dead animals and plant organic matter wastes. By which they release water and carbon and mineral components (recycling) which hugely contributes for our ecological balance, their inexistence might lead to death of all plants and animals because they are the main source of minerals for soil. |
| Talk about parasitic fungi. | Absorb nutrients from living organisms cells. Could be pathogens (diseases called (mycosis) in plants animals and humans. |
| Talk about symbiotic fungi. | establish mutual benefit associations with other living organisms; mycorrhizae, association between fungi and root of vascular plants
lichens association between fungi and algae cells or cyanobacteria |
| How are fungi present in nature? | Eukaryotic thallophytes, mainly terrestrial organisms occupying a variety of habitats, some are unicellular but most are filamentous. Branched fungal structures are called hyphae (tissue) that form a tangle mass known as the mycelium which constitutes the vegetative apparatus of fungi. Well developed fruiting bodies called carpophores or sporophore are only found in higher fungi. |
| Talk about the structure of a fungi. | In most of them hyphae are divided by septa (transverse wall) and consists of long linear cells, each containing one or two nuclei. Septum between two cells is perforated by a central pore allowing protoplasm of a cell to pass from one cell to another. Others are coenocytic, undivided by septa and something like an elongated multinucleated giant cell. |
| How is carbon reserved in fungi? | As glycogen, dispersed particles in cytoplasm, lipid inclusions are common in some fungi species, Main component of cell wall of fungi is chitin an amino acid polymer exists only in animal kingdom: scales or resistant exoskeleton of arthropods (insect...) More resistant to degradation than cellulose of plant cell wall |
| How are fungi classified? | Based on characteristics of sexual reproductive cycle, Four groups:
Zygomycota (zygomycetes)
Ascomycota
Basidiomycota
Chytridiomycota
Deuteromycota (artificial) groups all species with unknown sexual cycle. |
| Talk about Yeast. | Unicellular, not a true taxonomic group, some reproduce by asexual budding (deutromycetes) some reproduce sexually and belong to Ascomycetes, Basidomycetes and Zygomycetes. Used by bakers (to produce CO2) and winemakers for ethanol production. |
| What does dimorphic fungi mean? | They exhibit doth unicellular (Yeast) and filamentous (mycelium) growth forms, shifting from one to another under control of changing environment It is the case of most fungi that are pathogens to humans. Saccharomycete cerevisiae (Ascomycete) is a filamentous dimorphic fungi changes form when nitrogen is scarce (from yeast to filament). |
| Talk about Chytridiomycetes. | Chytrids are the only fungus to have a flagellated phase in their cycle, Almost all of their thalli are coencytic siphons, some are unicellular and don't form mycelium other have rhizoids enabling them to be fixed to the substrate. Some species of them are saprophytic feeding from animal and plants derbis, others are parasitic. |
| Talk about zygomycetes. | Fungi whose thalli is siphoned mycelium formed of siphons. Some are unicellular like yeast. Most are saprophytes and live on animal and plant decaying in soil. Some are parasites for plants animals insects... Others form symbiotic associations with plant roots (mycorrhizes) |
| Talk about basidiomycetes. | AKA club fungi, from club shaped basidia, distinguished by formation of basidiospores. (reproductive cells.)
Formed on top of mycelial hyphae and gathered in fruiting bodies called basidiocarps or carpophores. Form a cap (pileus) at the top of a stipe sometimes a volva at stipe base. Lower surface consists of perpendicular plates called gills, holding basidia that radiate from stalk to the edge of the cap and form hymenium. Most are saprophytic and play a role in wood (lignin) decomposition and cellulose derpis. Primitive fungi are deprived of carpophores like rusts and smut that are pathogens for vascular plants (cereals) Septated mycelium by sperforated septa |
| Talk about Deuteromycetes. | Imperfect fungi sexual reproduction (perfect stage) serve as a basis for fungal taxonomy is unknown and has not been observed in this group, so they are unclassifiable and a second (deutron-) class or as imperfect form comparing with sexually active ones. Saprophytic, some are human pathogens.
Great economical purposes Penicullium synthesizes antibiotics penicillin to treat bacterial infection. Also used in cheese manufacturing. |
| Talk about Lichens. | Symbiotic association between fungus and green photosynthetic unicellular or filamentous algae or cyanobacteria, partner (mycobiont) is most often Ascomycete, although it is sometimes Basidiomycete, while green algae are the photosynthetic partner (photobiont) (bios=life)
Fungus gives lichen its shape. Tissues made by hyphae represent most of lichens mass, fungus provides algae with ideal environment for growth and absorb essential minerals from air or rain. Aalgae constitutes in general from the internal layer providing food to Eumycetes.
Cyanobacteria fix atmospheric N2 and convert it into organic, play role in nitrogen giving for ecosystem |
| Talk about Mycorrhizae. | Symbiotic association with plants roots. Almost all vascular plats have it, Both benefit, Fungi provide minerals and plants provide organic elements. |
| Talk about Rhizopus stolonifer | or black mold is a saprophytic one that grows on cottony masses on food rich in carbs and exposed to air such as bread, fruits and vegetables. Mycelium consists of coencytic hyphae that rapidly develope through the food and absorb nutrients. Other curved hyphae or stolons are fixed to the substrate by rhizoids, and produce sporangiophores that hold their end the sporangia containing spores. |
