Chapter 31 Notes

Fungi

Concept 31.1

All fungi are eukaryotic; most are multicellular

mycete = fungiFungi differ from plants in nutritional

mode, structural organization, growth, and reproduction

Concept 31.1

Fungi are heterotrophs that acquire their nutrients by absorption- fungi digest their food outside their body by secreting powerful hydrolytic enzymes (exoenzymes) into the food.- decomposers, parasites, and mutualistic symbionts

Concept 31.1

Fungi have a large surface area and grow rapidly to assist with absorption

The bodies of fungi are constructed of tiny filaments called hyphae- the hyphae are divided into cells by cross-walls, or septa- cells walls are made of chitin

Concept 31.2

Fungi disperse and reproduce by releasing spores that are produced sexually and asexually- heterokaryotic stage: fusion of two hyphae that have genetically different nuclei

More than 100,000 fungi species are known; estimated that 1.5 million may exist

Phylum Chytridiomycota:- chytrids are mainly aquatic- saprobes or parasites- most primitive fungi; ancestors of protists

Phylum Zygomycota:- mostly terrestrial; live in soil or on decaying plants and animals- many form mycorrhizae, a mutualistic association with the roots of plants

Phylum Ascomycota:- sac fungi- range from unicellular yeasts to cup fungi- produce spores in saclike asci

Phylum Basidiomycota:- “club fungus”- mushrooms, puffballs, and rusts- important decomposers of wood and other plants

Concept 31.5

Molds, yeasts, lichens, and mycorrhizae have specialized lifestyles

Molds- a rapidly growing, asexually reproducing fungus

Yeasts- unicellular fungi that inhabit liquid or moist habitats

Concept 31.5

Lichens- symbiotic relationship of millions of photosynthetic microorganisms (alga) held in a mesh of fungal hyphae- the alga provides the fungus with food. The fungus provides a suitable environment for growth

Concept 31.5

Mycorrhizae- mutualistic association of plant roots and fungi- responsible for making nutrients able to be absorbed