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Biol 165 - Fungi.pdf

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University of Waterloo
BIOL 165
Kirsten Muller

Fungi Introduction • Fungi are polyphyletic and belong to 2 Kingdoms: Kingdom Protoctista and Kingdom Eumycota(Fungi). • are more closely related to animals than plants • Their food reserve is stored as GLYCOGEN, like animals. • the study of fungus is called Mycology. • Fungi have a diffuse body called a thallus or mycelium. • Hyphae: each of the branching filaments that make up the mycelium of a fungus. • Mycelium: the vegetative part of a fungus, consisting of a network of fine white filaments (hyphae). • The walls of the hyphal tube is mainly composed of chitin and/or cellulose. • They digest their food be secreting exozymes, which digests the food externally and allows the fungus to than absorb them. • Fungi have 3 modes of heterotrophic existence: o 1) Saprobic: process of chemoheterotrophic extracellular digestion involved in the processing of dead or decayed organic matter. o 2) Parasitic: an organism that decomposes living organisms and tissues. The arrangement only benefits the parasite. o 3) Mutualistic: is the way two organisms of different species exist in a relationship in which each individual benefits.  Mycorrhizae: a fungus that grows in association with the roots of a plant in a symbiotic or mildly pathogenic relationship. • Many mushrooms are toxic, or even lethal is ingested. • The role of Fungi is important as they decompose billions of tops of plant and animal material every year. The Mycelium • The mycelium is the “fungal body”, and is composed of many hair-like hyphae • hyphae are composed of cell wall with chitin and cellulose • The thickness and other features of hyphae can vary, depending on the species. Genus Armillaria • Forms stringy runners under the bark of trees. • can extend up to 100m or greater • can live for hundreds of years Phylogeny of Fungi • True fungi are related coanoflagellates and metazoa; all are in the SuperGroup Opisthokonta • Lower Fungi o Called Pseudofungi o Includes Phylum Oomycota and Phylum Chrtridiomycota • Higher Fungu o Lichens (include some algae) o Yeasts o Division Dikaryomycota and Division Zygomycota Pseudofungi – Phylum Oomycota • one of the lower fungi • Evidence suggests they are part of Chromista Clade, or SuperGroup Chromaveolata, in Kingdom Protoctista • They are oogamous, but can also reproduce asexually o Asexually via zoosporangia and heterokontous zoospores. • 2 Orders o 1 aquatic; Water Mold o 1 terrestrial; Downy mildews – converged with powdery mildews  cause extensive damage to crops o Order Peronosporales – Downy Mildews • Peronospora tabacina causes tobacco blue mold • Phytophthora infestans causes Potato Blights, as well as diseasing other plant species. o ie, Sudden oak death in California o Dogwood anthracnose in N. America • Plasmopara viticola causes downymildew in grapes Phylum Chytridiopmycota • often unicellular • develop within the host in 2 possible ways o 1) Holocarpic: within the hosts cells o o 2) Eucarpic: outside of host o • Life Cycle of a Chytrid – Rhizophidium o anisogamous • Eumycotan Fungi – Higher Fungi • Often called Kingdom Fungi – but misleading since it does not include all Fungi • includes higher fungi: o they form spores that are resistant to desiccation and have no flagellated cells at ANY point of Life Cycle. • Is a MONOPHYLETIC group of 3 Main Clades o 1) Phylum Zygomycota o 2) Phylum Dikaryomycota – Subphylum Ascomycota o 3) Phylum Dikaryomycota – Subphylum Basidiomycotina • There are non-monophyletic groups that are sometimes included o conidial fungi o yeasts o lichens Reproduction • utilize both asexual and sexual reproduction • Teleomorph: sexual phase in fungus • Anamorph: asexual phase of fungi – at times only phase observed in some species • Teleomorph + Anamorph = Holomorph • Fungi often have 2 names – one representing teleomorph and one representing anamorph. o The Teleomorph name is the Holomorph name. Phylum Zygomycota • includes saprobes that colonize terrestrial substrates (bread, fruit, etc.). • Some are parasitic on humans – called mucormycoses • Hyphae are thick, non-septate; fall apart if dried out. • Teleomorphs among phyla are similar, Anamorphs differ among phyla. •
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