Fungi - Introduction to the Fungi, Ecological
Impacts of Fungi, and Phylogenetic
Relationships of Fungi
Michael Cheng, Samir Raman, and Chris “Fun Guy” Zhu
Absorptive nutrition enables fungi to
live as decomposers and symbionts
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Fungi must obtain food
through absorption.
Saprobic fungi absorb
nutrients from nonliving
organic material.
Fungi that absorb from
live hosts are parasitic
fungi.
Organisms such as
lichen are mutualistic
fungi because the algae
and fungi work together.
Variation in lichen growth
forms.
Extensive surface area and rapid growth
adapt fungi for absorptive nutrition
FIGURE 31.1 – Fungal mycelia (p.575)
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Fungi allow ribosomes to flow from cell to cell through
the septa.
Much like early fly embryo, coenocytic fungi have many
nuclei in the cytoplasm with no cell walls.
FIGURE 31.2 – Characteristics of fungal hyphae (p.575).
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10 cubic centimeters
can contain 1 km
hyphae.
Parasitic fungi differ
from other fungi
because they have
haustoria in place of
hyphae.
FIGURE 31.2 –
Characteristics of
fungal hyphae
(p.575).
Fungi reproduce by releasing spores that
are produced either sexually or asexually
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When the
environment favors
rapid growth, fungi
will reproduce
asexually by
producing spores.
Fungal hyphae and
spores are haploid.
Mycelia may become
diploid due to the
fusion of hyphae.
FIGURE 31.3 –
Generalized life cycle
of fungi (p.576).
Syngamy – sexual union of cells
from two individuals in kargogamy
(fuse nuclei) and plasmogamy
(fuse cytoplasm)
 This process produces dikaryon,
which are two nuclei
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Ecosystems depend on fungi as
decomposers and symbionts
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Wood rotting fungi became a dominant group
of organisms about 250 million years ago
during the mass extinctions that occurred at
the end of the Permian era.
Fungi and bacteria are principal decomposers
that supply the ecosystem with essential
inorganic nutrients.
Their invasive hyphae hydrolyze polymers
within the lining of the cell wall.
During the Revolutionary War the British lost
more ships to fungal rot than to enemy attack!
Some fungi are pathogens
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Athlete’s Foot, a yeast infection (EWW!) and many lung infections are
all due to fungus.
The Dutch elm disease changed the landscape of the Northeast when
logs that carried the fungus from Europe were shipped to the US
during WWI.
Some fungi such as Aspergillus contaminate grain by secreting
compounds called aflatoxins, which are carcinogenic.
Some fungi such as lysergic acid (a main component of LSD) are
strong hallucinogens…trust me.
Many animals, including
humans, eat fungi
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Many plants and animals
(including humans!)
consume a variety of
fungi
The most common
example is the
mushroom. The most
prized mushroom is the
truffle, which is
renowned for its great
taste and versatility
Mushrooms often emit
odors through their
spores to attract animals
to eat them.
Jeremy Clarkson of Top
Gear with an expensive
fungus.
Fungi and animals probably evolved
from a common protistan ancestor
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Molecular evidence
supports that the four
fungal divisions are
monophyletic.
The occurrence of
flagella in the chytrids
indicates that fungi and
animals have a common
ancestor.
Fungi and animals
probably evolved from
aquatic flagellated
organisms.
Comparisons of several
proteins and ribosomal
RNA indicate that fungi
are more closely related
to animals than to
plants.