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The Fungi
Unit 5
Donna Howell
Medical Microbiology
Gaffney High School
The Tree of Life
• In 1959, American
scientist R. H.
Whitaker added the
kingdom Fungi to the
currently-existing 4
kingdom system.
Classification of Fungi
• Fungi are classified
according to their
structure and
method of
reproduction.
Did someone
mention the
birds and the
bees?
What Is A Fungus?
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•
•
•
•
•
•
•
Eukaryotes
Kingdom: Fungi
Mostly terrestrial
Multicellular (except
yeasts)
Cell walls of chitin (a
polysaccharide)
Heterotrophic
Store food in form of
glycogen
Sexual and asexual
reproduction
Structure of Fungi
• Fungi are composed
of many filaments
called hyphae. Each
hypha is one cell
thick, and each cell
can contain one or
more nuclei. Some
cells are separated
by cross walls called
septa, some are not.
Individual
hyphae
Structure of Fungi
• The body of fungi
are composed of
many hyphae
tangled together
into a thick mass
called a
mycelium!
Did You Know?
• A person that studies
fungi is called a
mycologist!
Did You Know?
• That in 1845, a
fungus attacked the
potato crop in
Ireland causing the
Great Famine?
Did You Know?
• A fairy ring is a ring
of mushrooms
growing above
ground from one
common mycelium
below ground?
How Do Fungi Obtain Their Food?
• Heterotrophic
• Digest organic
matter by excreting
enzymes into the
environment and
absorbing byproducts
• Store carbohydrates
as glycogen instead
of starch like plants
How Do Fungi Spread?
• By way of spores!
The spores scatter in
the wind or on the fur
or foot of an
unsuspecting
animal.
• Spores will actually
germinate when
moisture,
temperature, and
food source are all
right!
Groups of Fungi
• Fungi are classified
into 4 main groups:
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–
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Zygomycota
Ascomycota
Basidiomycota
Deuteromycota
• Each as a different
type of reproductive
structure
Zygomycota (Common Molds)
• These are the
familiar molds that
grow on meat,
cheese and bread.
• Reproductive
structure =
zygospore
Zygospore
Zygomycota Structures
• Rhizoids – rootlike
structures that
penetrate surface
and serve as
anchors
• Stolons – hyphae
that run along the
surface of object
• Sporangiophores –
hyphae that shoot up
into the air with
zygospores on them
Zygomycota Example
• Rhizopus
stolonifer – the
common black
bread mold.
Important in
industrial
applications.
Ascomycota (Sac Fungi)
• These are such
things as yeast,
Penicillium sp, and
others
• Reproductive
structure =
ascospore
Ascospore
Ascomycota Structures
• Ascus is a
reproductive
structure that
contains spores (like
a sac). In a moist
environment, these
spores become
active.
Ascomycota Examples
Common Bread Yeast
Penicillium sp.
Aspergillus sp.
Used in industry to produce various
products
(Source of penicillin)
Yeasts
• Single-celled oval
microbes which
reproduce by
budding.
• Important because
used in baking and in
the making of foods
such as beer and
wine.
• Play a large role in
genetic engineering.
Budding Yeast
Basidiomycota (Club Fungi)
• This group
includes the
mushrooms,
puffballs,
stinkhorn fungi,
shelf fungi
• Reproductive
structure
=basidium
Basidiomycota Structures
• The basidium is the
spore-bearing
structure, and it
resembles a club.
• Found on the
underside of
mushrooms.
Basidium
Basidiomycota Examples
Shelf Fungus
Puffball
Amanita phalloides
“The Death Cap”
Deuteromycota (Imperfect Fungi)
• This group includes
the fungi that are not
placed in another
group because no
sexual cycle has
been observed (yet!)
• Reproductive
structure =Conidium
Deuteromycota Structures
• Conidium is the specialized spore for these
fungi.
Deuteromycota Examples
• Alternaria, which is
both ubiquitous and
abundant, is both
saprophytic and
parasitic on plant
material and is found
on rotting vegetation
as well as in damp
indoor areas, such
as bathrooms.
Reproduction of Fungi
•
Can reproduce in
one of two ways:
1. Sexual
reproduction
2. Asexual
reproduction
Sexual Reproduction in Fungi
• Two mating types: a
+ and a –
• When + and – hyphae
meet, a
gametangium is
formed, which
creates gametes.
• Meiosis occurs,
producing new
fungus.
Asexual Reproduction in Fungi
• Can occur in two
ways:
– Fragmentation –
piece breaks off,
becomes new hyphae
– Mitosis – single cell
produces two
genetically identical
daughter cells
Ecology of Fungi
• Important to many
ecosystems
because:
– Decompose dead
organisms
– Live in association
with other organisms
in a mutually
beneficial way
– Can act as parasites,
causing disease
Decomposers
• Fungi recycle
nutrients by
breaking down the
bodies and wastes of
other organisms.
Perpetuate the
“circle of life”.
Parasites
• Can cause plant and
animal diseases as
well as human
disease. Examples:
wheat rust, athlete’s
foot, thrush, etc.
Responsible for Irish
Potato Famine.
Symbionts
• Lichens – mutually
beneficial
relationship between
fungus and a plant.
• Mycorrhizae –
mutually beneficial
relationship between
plant roots and
fungus.
Did You Know?
• Mycorrhizae affect
about 80% of the
world’s plants – they
help the plant absorb
water and minerals,
and the plant
provides the fungus
with the products of
photosynthesis.
Plants wouldn’t exist
without them!
Candida albicans
• Cause of female
yeast infection
• Normal in vaginal
tract, but if
overgrows, a
problem
• Itching, burning,
white “cottage
cheese” discharge
Cryptococcus neoformans
• One cause of
meningitis,
transmitted by
breathing in pigeon
droppings.
• Piercing headaches,
stiff neck, paralysis.
Tinea sp.
• Causes many human
diseases:
– Athlete’s foot
– Jock itch
– Ringworm
• Symptoms:
redness, itching
Ringworm Fungus
Coccidioides immitis
• Respiratory infection
of humans from
breathing in bird
droppings
• Found mostly in SW
United States
• Fungus gets in lungs
and causes flu-like
illness
Histoplasma capsulatum
• Also associated
with breathing in
bird droppings,
especially near
barns and sheds.
• Causes a mild
respiratory illness.
Video Clip
The End!