Chapter 19 part II
Fungi
General characteristics
Variety of moist habitats
 Variety of sizes and colors
 Variety of temperatures
 All decompose large amounts of organic
waste materials

Fungal structure
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Hyphae
Develop from spores
 Branch to form a network of mycelium
 Divided by cross walls (septa)
 Cytoplasm passes through pores in septa to
allow transport of nutrients
 Some hyphae have no septa
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Fungal structure

Cell walls

Made of chitin (carbohydrate)
Food getting

Extracellular digestion
Food is digested outside of fungus cells
 Hyphae release enzymes to digest food and
nutrients released are absorbed (pass into
cells by diffusion or facilitated diffusion)

Food getting
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Feeding relationships of fungi and plants
Fungi absorb nutrients from plants but provide
the plant with water and minerals
 Some fungi parasitize plants and animals
(athlete’s foot, yeast infections, tree fungus)
 Some fungi are decomposers and use dead
organic materials for nutrients

Reproduction is asexual

Fragmentation

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Budding

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Pieces of hyphae break off and grow new
mycelia
Mitosis occurs producing new individual fungi
which separates from the parent cell
Spores

Reproductive cells made that germinate and
develop into new organisms
Classification

Fungi are classified by spores produced in
sexual reproduction or meiosis
Adaptations

Spores
Small and light weight for easy dispersal
 Produced in large quantities
 Can be dispersed by wind, water, animals,
insects

Phyla of fungi
Zygomycota-Zygospore forming
 Ascomycota-Sac forming
 Basidiomycota-Mushroom forming
 Deuteromycota-no sexual reproduction
 Mutualistic

Mycorrhiza-fungi and plants
 Lichens-fungi and algae or cyanobacterium

Zygomycota



Form zygospores
Decomposers
Reproduce asexually w/ spores


Hyphae grow upwards and release spores
Reproduce sexually w/ thick-walled spores



Triggered by environmental change
2 hyphae come in contact and fuse to form haploid
gametangia
Gametangia fuse to form zygote that develops into
zygospore
Zygomycota continued

Growth
Stolons are hyphae that grow horizontally on
the surface of a food source
 Rhizoids penetrate the food to anchor
mycelium and are the site of extracellular
digestions and nutrient absorption

Ascomycota
Sac fungi are largest group w/30,000
species
 Produce asci (sacs) that contain sexual
spores (ascospores)
 Asexual reproduction

Hyphae rise up from mycelium to produce
asexual spores
 Spores are dispersed by wind, water, animals

Ascomycota continued

Importance
Decompose food products
 Cause plant diseases

 Apple
scab, Dutch elm, ergot
 Some attack people and animals

Some are edible
 Morels
 Truffles
 Yeasts
(food and research)
Basidiomycota
Club fungi include mushrooms, puffballs,
stinkhorns, bracket fungi, smuts, rusts
 Basidia (club shaped hyphae) produce
spores
 Mushroom (stalk and cap) produce sexual
spores for a short period of time (p. 570)

Deuteromycota
NO known sexual reproduction
 One type produces penicillin
 Some used in soy sauce and cheese
 Some used to produce citric acid

Mutualism

Mycorrhiza: fungus and plant roots
Fungus increases amount of nutrients
absorbed by the plant: P, Cu, other minerals
 Fungus keeps soil damp around plant roots
 Plant gives fungus organic nutrients like sugar
and amino acids
 80-90% of all plants have mycorrhiza

Mutualism continued

Lichens-fungus with a green alga or
cyanobacterium
Fungus provides habitat and retains moisture,
gives minerals to alga and protects from
sunlight
 Alga photosynthesizes and gives fungus food
 Only need light, air and minerals
 Found in every environment

Lichens
Lichens