Fungi
Ch. 22
pp. 482-95
Kingdom Fungi - Characteristics
• Fungi first appeared on earth around 430
million years ago.
• In the past, fungi were grouped with plants
because they shared several common
features:
– Immobile
– Cell wall
– Some appear rooted in the soil (mushrooms)
Characteristics Cont’d
• Key Characteristcs of Fungi:
– Heterotrophic • Energy comes from breaking down organic
material in the environment.
– Multicellular
– Filamentous Bodies • Made of long, slender filaments that are tightly
woven together to form the body of the fungus.
– Cells contain chitin • Tough polysaccharide found in the cell walls of
fungi.
Structures • Hyphae compose the body of the fungi (except
yeast)
– slender filaments
– long string of cells divided by partial walls
allowing cytoplasm to flow freely between
cells
Structure continued • Mycelium is a tangled mass of hyphae
• This complex of hyphae (mycelium) gives
the fungus a high surface- area-to-volume
ratio.
• Can be many meters in length.
How would this benefit the fungus?
ANSWER
– Has the ability to absorb more nutrients from
the environment.
Cell Walls
• Made of chitin
• Chitin is also found in the exoskeleton
of insects
• It is a polysaccharide
– What type of biological macromolecule
is this?
Nutrition
• HETEROTROPHIC
• saprobe: obtains energy by breaking down organic material
• digestive enzymes are secreted by fungi to break down organic material and the compounds are then absorbed for energy
• organic material used by fungi for energy:
– dead leaves, branches, dead animals, waste
– living hosts are parasitized by fungi like ringworm and athletes foot
Ring Worm of the Scalp
Athlete’s foot
RING WORM
Apply antifungal medications to the lesion itself
and 1 inch beyond its border twice daily for a
minimum of two weeks, and at least one week
after it goes away. Keep the infected area clean
and dry. Medications available at the drugstore
include miconazole 2% (with brand names such
as Monistat and Micatin) or clotrimazole 1% (with
brand names such as Lotrimin and Mycelex).
-Ringworm is highly contagious.
-Avoid touching suspicious lesions.
-Maintain proper hygiene by washing your hands
and body frequently
-Avoid contact sports such as wrestling until you
have been treating the lesions for at least 48
hours.
ATHLETES FOOT
Keep the area clean and dry. Buy shoes that are leather or other
breathable material. Powders, especially medicated powders
(such as with miconazole or tolnaftate), can help keep your feet
dry.
Soak feet in a drying solution of aluminum acetate (Burrow's
solution or Domeboro's solution). A homemade remedy of dilute
white vinegar soaks using one part vinegar and roughly four parts
water, once or twice a day as 10-minute foot soaks may aid in
treatment.
Use antifungal creams and washes (miconazole or Lamisil)
Treatment for athlete's foot should generally be continued for four
weeks, or at least one week after all of the skin symptoms have
cleared.
Reproduction
• Can be sexual or asexual
• Occurs through the release of spores from
structures at the tips of hyphae.
• Reproductive Strategies:
– Reproductive structures grow high above the food
source.
– This adaptation allows air currents to carry spores to
a new habitat.
– Spores are very light and can be carried great
distances before falling back to the ground.
Fungus releasing spores
Review: a spore is like a tiny seed
• Light weight, can float long distances
• Can withstand extreme conditions until the
environment is favorable for germination
Asexual Reproduction
• Some may have filaments that break from
the main mycelium and grow into new
individuals
• Some produce spores that disperse,
germinate, divide and produce genetically
identical fungi
– Spores can withstand extreme dryness and
cold to produce new fungi when conditions
permit
Sexual Reproduction
• Fused hyphae form a sexual reproductive
structure
• On this structure, the fungus forms spores
through fusion of two genetically different
nuclei.
• The type of structures produced during
sexual reproduction determine the Phyla
to which a species belongs.
Reproductive Structures
• Based on the structures formed during
sexual reproduction, fungi can be grouped
in 4 phyla:
– Chytridiomycota
– Zygomycota
– Ascomycota
– Basidiomycota
Chytridiomycota
• Most ancient of fungus
• Have motile spores
• Live in water
• Are killing frogs world wide
Carcass of frog killed by a Chytridiomycota
Zygomycetes – Molds
• Species of Rhizopus or bread
molds
• Sexual structures have thick walls
zygosporangia
• Usually live in the soil and feed on
decaying plant and animal matter.
• Other anatomical structures:
– Stolon: mycelia that grow on surface
– Rhizoids: hyphae that anchor the
fungus in the bread
haploid
haploid
haploid
Zygomycetes
• Reproduction:
– Asexual
– Haploid spores are produced in the
zygosporangia.
– When the haploid spores mature, they are
released and carried by the wind to new
locations.
– In the new location they germinate and
grow new mycelia.
– Spores like these cause fungal allergies
Ascomycetes-Sac Fungi
• Examples: – Endothia parasitica
Kills chestnut trees
– Saccharomyces cerevisiae
Baker’s yeast
– Candida albicans Causes thrush
• Sexual Structure: Ascus – Sac-like structure in
which haploid spores are formed.
Yeast asexually reproducing by BUDDING
Oral Thrush, common in infants
Basidiomycetes-Club Fungi
• Examples: Mushrooms, toadstools, puffballs, jelly fungi, and shelf fungi.
• Sexual Structure = basidium – Club-like structure where
spores are produced.
• Asexual reproduction is rare and occurs mainly in rusts and smuts (plant pathogens).
DEATH CAP MUSHROOM
• Toxin blocks production of DNA (why is
this a problem?)
• Causes nausea, kidney and liver failure,
coma and DEATH in 30% of all people
who ingest them.
• Mutualism: type of symbiotic relationship
in which each partner benefits.
• LICHENS
– Fungus (heterotrophic), provides minerals and
other nutrients absorbed from the
environment.
– Algae or Plant (photosynthetic autotroph)
provides the ability to use sunlight to build
carbohydrates.
Fungal
Relationships
Mycorrhizae
• Relationship between fungi and vascular plant roots.
– Hyphae help transfer phosphorus and minerals to the roots of plants.
– The plants provide carbohydrates to the fungus.
– What kind of symbiotic relationship is this?
Parasitic Fungi
• Parasitism:
– A form of symbiosis where one
organsim benefits from the
other species, and usually
causes harm to the host.
• Parasitic fungi compete for
nutrients with the host and
sometimes cause infections:
– Athlete’s Foot
– Yeast Infections
– Histoplasmosis
• Fungal infection of the lungs
• Caused by the fungus
Histoplasma capsulatum
Fungi in your life
• Fungi often grows on food, such as bread
and fruits.
• Yeasts are useful in baking, brewing, and
wine-making.
• Fungi provide the aroma and flavor of some
cheeses.
• Many antibiotics are produced from fungi…
– penicillin
– streptomycin