Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Evolution of Multicellular Life Chapter 15 Copyright © McGraw-Hill Companies Permission required for reproduction or display

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Outline Complex Multicellularity Fungus vs. Plants Fungal Reproduction and Nutrition Fungi Ecology Kinds of Fungi  Zygomycetes  Ascomycetes  Basidomycetes Lichens and Mycorrhizae

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Complex Multicellularity Individuals are composed of many highly specialized kinds of cells that coordinate their activities. Three Kingdoms:  Plants  Animals  Fungi

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Complex Multicellularity Two key characteristics separate complex multicellular organisms from simple multicellular organisms.  Cell Specialization - Different cells using different genes - Cell Development  Intercell Coordination - Cell activity adjusts based on response to functions of other cells.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies A Fungus Is Not A Plant Differences between fungi and plants:  Fungi are heterotrophs.  Fungi have filamentous bodies.  Fungi have nonmotile sperm.  Fungi have cell walls made of chitin.  Fungi have nuclear mitosis. Copyright © McGraw-Hill Companies Permission required for reproduction or display

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies A Fungus Is Not A Plant Body of a Fungus  Fungi exist mainly in the form of slender filaments (hyphae). - Walls (septa) divide cells in filament.  Main body is network of hyphae (mycelium). - All parts of body are metabolically active. - Because of cytoplasmic streaming, many nuclei may be connected by shared cytoplasm.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Fungal Reproduction and Nutrition Fungi reproduce both asexually and sexually.  Sexual reproduction initiated when hyphae of genetically different mating types come in contact and fuse. - Heterokaryon - nuclei derived from genetically different individuals. - Homokaryon - nuclei derived from genetically similar individuals.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Fungal Reproduction and Nutrition Three kinds of reproductive structures:  Gametangia - Gametes form within  Sporangia - Spores form within  Conidia - Asexual spore Fungi obtain food by secreting digestive enzymes into their surroundings and absorb organic molecules produced by external digestion.  Some act as active predators.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Fungi Ecology Fungi and bacteria are principle decomposers in biosphere.  Fungi virtually only organism capable of breaking down lignin.  Often act as disease-causing organisms for plants and animals.  Multiple commercial products depend on biochemical activities of fungi. - Cheese, Penicillin

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Kinds of Fungi Nearly 73,000 described species. Three fungal phyla are distinguished from one another primarily by mode of sexual reproduction.  Zygomycetes  Ascomycetes  Basidiomycetes

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Zygomycetes Zygomycetes are unique among fungi because fusion of hyphae does not produce heterokaryon.  Two nuclei fuse and form diploid nucleus.  Make up only about 1% of named fungi.  Reproduction typically asexual.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Life Cycle of Zygomycete

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Ascomycetes Ascomycetes is largest of three phyla with about 32,000 named species.  Reproduction usually asexual.  Hyphae possess septa that divide cells.  Named for characteristic sexual reproductive structure (ascus) which differentiates within the ascocarp.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Life Cycle of Ascomycete

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Basidiomycetes Basidiomycota contains most familiar fungi (mushrooms, toadstools, rusts and smuts). Life cycle starts with production of hypha from a germinating spore. In sexual reproduction, zygotes from when two nuclei of dikaryotic cells fuse.  Occurs within club-shaped reproductive structure (basidium).

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Life Cycle of Basidiomycete

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Unicellular and Asexual Fungi Yeasts  Generic name given to unicellular fungi. - About 250 named species.  Most yeast reproduction is asexual and takes place by cell fission or budding. Imperfect Fungi  Sexual reproduction never observed. - Cannot formally be assigned to one of sexually reproducing phyla.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Lichens Symbiotic association between fungus and photosynthetic partner.  Most of visible body consists of fungus, with interwoven cyanobacteria or green algae. - Fungus transmits biochemical signals to partner directing production of metabolic substances.  Key component of primary succession.  Can resist drying or freezing.  Pollution indicators.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Mycorrhizae Mycorrhizae are associations between fungi and plant roots.  Fungus filaments act as efficient root hairs, and aid in direct transfer of minerals while plant supplies organic carbon to the symbiotic fungus.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Mycorrhizae Endomycorrhizae - Fungal hyphae of mycelium penetrate outer cells of the plant root, as well as far into the soil. Ectomycorrhizae - Mycorrhizae surround but do not physically penetrate plant root cells.  Highly specialized relationships in which a particular plant species has become associated with particular fungus.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Review Complex Multicellularity Fungus vs. Plants Fungal Reproduction and Nutrition Fungi Ecology Kinds of Fungi  Zygomycetes  Ascomycetes  Basidomycetes Lichens and Mycorrhizae

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Copyright © McGraw-Hill Companies Permission required for reproduction or display