Chapter 21

21-1 The Kingdom Fungi


Fungi are eukaryotic heterotrophs that have cell walls made of chitin (a carbohydrate).

Fungi DO NOT ingest their food, but rather they digest food OUTSIDE their bodies and the ABSORB it! (Fungi are decomposers)
Reasons Fungi Not Plants!

No chlorophyll



Cell wall not Cellulose
NO vascular tissue
Do not photosynthesize
(Not an autotroph)


Structure and Function




Multicellular (except yeasts)
Composed of hyphae—thin filaments one cell thick
Cross walls—cytoplasm and nuclei can move through openings
Without cross walls—contain many nuclei

Nuclei
Cell wall
Cytoplasm
Cross wall
Nuclei
Cytoplasm
Hyphae With Cross Walls
Cell wall
Hyphae Without Cross Walls
Section 21-1


Except for yeasts, ALL fungi are multicellular and composed of tiny filaments called hyphae.



The bodies of multicellular fungi are composed of many hyphae tangled together into a thick mass called a mycelium.
The mycelium is well suited to absorb food.
The fruiting body is a reproductive structure that develops from a mycelium that grows below the surface of the ground.

Hyphae
Fruiting body
Mycelium
Section 21-1


Most fungi reproduce both asexually and sexually.
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Asexual:

In some fungi, spores are produced in structures called sporangia.

Sporangia are found at the tips of specialized hyphae called sporangiophores.
Sexual:

Sexual reproduction involves a gametangium - a gamete-forming structure produced when the hyphae of opposing mating types of fungi meet.


How Fungi Spread

Fungal spores

Scatter easily in the wind


Must land in favorable environment
 Temperature
 Moisture
 Food
Some are specialized to lure animals, flies
 Disperse spores over long distances

21-2 Classification of Fungi


Fungi are classified according to their structure and method of reproduction
The 4 main groups of fungi are:
1.
Zygomycota (common molds)
2.
Ascomycota (sac fungi)
3.
Basidiomycota (club fungi)
4.
Deuteromycota (imperfect fungi)


Zygomycetes are the familiar molds that grown on meat, cheese, and bread.

Ex: Rhizopus stolonifer (black bread mold).
the rootlike hyphae that anchor the fungus to the bread are called rhizoids the stem-like hyphae that run along the surface of the bread are called stolons

Figure 21-5 The Life Cycle of Rhizopus
Section 21-2 p. 531
Spores (N)
Sporangiophore
Asexual
Reproduction
Sporangium
Zygospore
(2N)
FERTILIZATION
Gametangia
MEIOSIS
Sporangium
Spores
(N)
Zygospore (2N)
Stolons
+ Mating type (N)
- Mating type (N)
Sexual Reproduction
Rhizoids
Diploid
Haploid

Zygomycota


The phylum Ascomycota is named for the ascus, a reproductive structure that contains spores.

Ascomycetes are the largest phyum in the kingdom Fungi.

Some are large and some are microscopic.

Examples: cup fungi (large) and yeasts (microscopic).

Figure 21-7 The Life Cycle of an Ascomycete
Section 21-2 p. 533
Diploid
Haploid
Hyphae
(N + N)
Fruiting body (N + N)
Ascus
(N + N)
Zygote (2N)
Gametangia
HYPHAE FUSE
Hyphae (N)
+ Mating type (N)
- Mating type (N)
Asci
Sexual Reproduction
FERTILIZATION
MEIOSIS
Conidia (N)
Conidiophore
Hypha (N)
Asexual Reproduction
Hypha (N)
Ascus
8 Ascospores
(N)


Yeasts

Unicellular fungi


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Ascomycetes—baking and brewing
Budding—process of asexual reproduction—cell division
Alcoholic fermentation to obtain energy
 Byproducts—carbon dioxide and alcohol

Candida sp.

Scarlet Cup Fungus
Morel

Ascomycota

CUP FUNGI
(visible to the eye)
YEASTS
(microscopic)



The phylum Basidiomycota gets its name from a specialized reproductive structure
(called a basidium) that resembles a club.
Includes:

Mushrooms
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Shelf fungi
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Puffballs
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Earthstars
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Jelly fungi
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Plant rusts

Bird’s nest fungi

Section 21-2 p. 534
Button
Figure 21-8 The Life Cycle of a
Basidiomycete
Fruiting body (N + N)
Gills lined with basidia
Cap
Gills
Stalk
Base
Basidia
(N + N)
FERTILIZATION
Secondary mycelium (N + N)
HYPHAE FUSE
Primary mycelium (N)
- Mating type (N)
Zygote (2N)
Haploid
Diploid
+ Mating type (N)
Basidiospores (N)
MEIOSIS

Mushrooms – “Club Like” Fungi or Basidiomycete Fungi

Basidiomycota

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Diversity of Club Fungi

Mushrooms

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Shelf fungi
Puffballs
Earthstars
Jelly fungi
Rusts
Edible and Inedible Mushrooms

Almost identical

Some inedible can cause severe illness or death

EARTH STAR
PUFFBALL
SHELF FUNGI
MUSHROOM
BIRD’S NEST FUNGI
JELLY FUNGI


Deuteromycota is an extremely varied phylum composed of those fungi that are not placed in other phyla.


The term imperfect implies that these fungi do not appear to have sexual reproduction.
Ex: Penicillium notatum
– the source of antibiotic penicillin.

Deutoeromycota

-Regarded as imperfect because they exhibit no sexual stage has been observed in their life cycle
-Members are not closely related and are not necessarily similar in structure or appearance; do not share a common ancestry, polyphyletic = coming from many ancestors – hmm weird


Truffles are round, warty, fungi that are irregular in shape. They vary from the size of a walnut to that of a man's fist. Since the times of the
Greeks and Romans these fungi have been used in Europe as delicacies, as aphrodisiacs, and as medicines. They are among the most expensive of the world's natural foods, often commanding as much as $250 to $450 per pound.
Truffles are harvested in Europe with the aid of female pigs or truffle dogs, which are able to detect the strong smell of mature truffles underneath the surface of the ground. The female pig becomes excited when she sniffs a chemical that is similar to the male swine sex attractant. The use of dogs to find truffles is also and option.

21-3 Ecology of Fungi
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All Fungi Are Heterotrophs
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Saprobes - Organisms that obtain food from decaying organic matter
Parasites - which harm other orgnisms
Symbionts - live in close and mutually beneficial association with other species
Capture live animals

Pleurotus ostreatus

Lives on the sides of trees and trap worms to digest them

21-3 Ecology of Fungi
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Fungi as Decomposers

Maintain equilibrium in nearly every ecosystem by recycling nutrients

Release digestive enzymes that break down organic material into simple molecules which diffuse into the fungus

21-3 Ecology of Fungi
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Fungi as Parasites


Cause serious plant and animal diseases and a few cause diseases in humans
Plant Diseases

Smuts, mildews, rusts
Spruce rust
Corn smut
Plant mildew

21-3 Ecology of Fungi
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Parasitic fungi cause serious plant and animal diseases:

 wheat rust mildew on fruit

Rust infecting wheat leaves
Rust infecting a Leaf
Whitrot Smut digesting old wood

21-3 Ecology of Fungi

Human Diseases



Athlete’s foot, ringworm
Candida albicans
(yeast)—oral thrush
Bacteria and yeast in the human body keep each other in check

21-3 Ecology of Fungi
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Other Animal Diseases

Cordyceps— grasshoppers in rain forests in Costa Rica

21-3 Ecology of Fungi
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Symbiotic Relationships
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Mutualistic (both benefit)
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Lichens
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Fungus and an alga or a cyanobacterium or both
Live mostly on bare rock and in places that most other organisms cannot live
Break down rock into soil
Autotroph makes food, fungus absorbs water and nutrients and serves as an anchor

Lichens are mutualistic symbiotic organisms. They have an
____________ fungus and a
_________ or cyanobacterial portion. There are three lichen growth forms which are predominant in nature: _____________________
_____________________________

Crustose
Foliose
Fruticose


Lichens


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A symbiotic associations between a fungus and a photosynthetic organism.
Lichen can grow on dry, bare rock and are often the first organisms to inhabit an area (pioneer species).
The lichen break down the bare rock, allowing other plants to grow.
lichen


Mycorrhizae

A symbiotic associations of plant roots and fungi.

Fungi increases the surface area of the plants roots.

Its presence is often necessary for the growth of many plants.
mycorrhizae

21-3 Ecology of Fungi

Mycorrhizae

Plant roots and fungi

Plant roots provide energy and fungus provides a large surface area for more absorption of water and minerals

Mycorrhizae

Phylum Ex’s
Zygomycota Bread Mold
Rhizopus a dung fungus
Ascomycota Yeast, morels, truffles
Characteristics
Chitin cell walls
Coenocytic = hyphae lack crosswalls
Asexual
Unflagel. spores drop from sporangia
Conidia on conidophores
Sexual
Gametangia fuse to create zygospore
Hyphae + & fuse to create ascospores in ascus
Basidiomycota Mushrooms
Puffballs, rusts, smuts
Fungi
Imperfecti
Deuteromycota
Penicillium,
Athlete’s
Foot fungus,
Tomato
Blight
Cross walls in hyphae
Similar
To
Basidio and
Zygomy
Asexual by way of
Conidophores which produce conidiospore s
Asexual by conidia which produce conidophores
Sexual when hyphae fuse in
BASIDIA to produce basidiospores
Sexual repro
Not known