Chapter 20
Lecture Outline
Eukaryotic Diversity: Fungi
Phylogeny of Eukaryotes

Eukaryotes have greatest diversity of size and
shape
 Unicellular



Fungi
Algae
Protozoa
 Multicellular
 Complex


multiorgan species
Less diverse metabolism than prokaryotes
50- 90% of their DNA consists of non-coding
sequences
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Phylogeny of Eukaryotes Based on Molecular and
Morphological Data
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Alignment of Peptide Sequences for
Elongation Factor EF-1a Reveals Insertion
in Opisthokont Species
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Opisthokonts
Includes animals, fungi, microsporidians
 Insertion sequence in EF-1a gene
 Single (unpaired) basal flagellum on
reproductive cells [usually]

 Humans:

sperm
Name means: “backward spread”
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Fungi (Eumycota)

Cell walls contain chitin

Strong acetylated polysaccharide



Beta-linked polymer of N-acetylglucosamine
Exoskeleton of insects
Cells cannot extend pseudopods

Must absorb food as individual molecules


Cannot ingest particulate food
Secrete digestive enzymes and absorb cleavage products
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Significance of Fungi



Recycle biomass of woods and
leaves
Ferment plant material within animal
digestive systems
Antibiotic production


Aflatoxin B
Penicillin
Fermentation


Normal Liver
Cheese, wine, bread etc.
Pathogens


Hepatocellular carcinoma
Aflatoxins and primary liver cancer
Opportunistic infections in
immunocompromised (local or systemic)
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Yeasts and Molds

Yeasts

Molds
 Unicellular
 Multicellular
 Budding
 Septated
(w/scaring
and senescence)
or non-
septated
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Dimorphic Fungi
Temperature
Yeast
Mold
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Reproduction of Fungi


Asexual
Mitosis
 Both

Sexual
 Meiosis
in 1n or 2n forms


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Haploid cells
Haploid cells fuse
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Classification of Fungi

Major groups include
 Chytrides
 Ascomycota
 Basidiomycota
(mushrooms)
 Zygomycota
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Fungi—Chytrids

Motile germ cells
 Flagellated

zoospores
Haploid or diploid
 Similar
to animals,
choanoflagellates


Flagellated reproductive form
Associations with animals
 Symbionts
in rumen
 Pathogens
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Fungi—Ascomycetes

Unfused nuclei pair before fusion
 Mycelia
form before nuclear fusion
 Fruiting body forms
 Meiosis generates gametes
 Fusion of cytoplasm,
not nuclei

Bread mold
 Neurospora

Penicllium
 penicillin

Aspergillus
 Opportunistic
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infections
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Aspergillus
Asexual spores
Sexual spores
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Fungi—Zygomycetes

Nonmotile sporangiospores
 Spread

Rhizopus
via air or water currents
Haploid mycelium
 1n
sporangiospores
 2n zygospores


Bread mold (Rhizopus)
Arbuscular mycorrhizae
 Essential

for plant roots
Increase root absorption
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