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Biology Chapter 11
The Kingdom Fungi
How do fungi differ from plants?
1. Lack true tissues
2. Lack chlorophyll
How do fungi differ from algae?
1. Lack chlorophyll
2. Completely heterotrophic (saprophytic or parasitic or
both)
How are fungi harmful?
1. Some can cause disease (example: page 297, ergot of rye,
"St. Anthony's fire") or even death
2. Crop damage
fungicide- a chemical substance used to kill or inhabit
the growth of fungi
How are fungi beneficial?
1. Provide leavening for breads [leavening- a substance
which provides bubbles of gas in doughs or batters
("rise")]
2. Decompose organisms in the soil and damp areas (most
important and most common)
3. Source of food (mushrooms and cheeses)
4. Medicines (penicillin) Alexander Fleming, 1929, First
antibiotic
Classification of Kingdom Fungi:
Phylum Eumycophyta- true fungi; 47,000 species; (mushroom,
mold, rust, yeast, smut); larger and more important
Phylum Myxomycophyta- slime molds; 450 species
Phylum Eumycophyta
The True Fungi
Most fungi are multicellular and have a distinct threadlike
structure or filaments, which form the body of a fungus (called
hyphae). Yeasts are unicellular.
types of hyphae:
Septate - hyphae that has a wall separating the individual
cells
the wall is called the septum (septa plural)
Nonseptate - hyphae that lack septa
see page 300
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Hyphae serve different functions and are named accordingly:
1. Rhizoids - embedded in the material on which the fungus
is growing; support the fungus and digests food
2. Aerial hyphae - not embedded in the material; absorb
oxygen, produce spores, and spread the fungus
3. Stolons - aerial hyphae that produce new filaments
4. Sporophores - hyphae branches which produce spores
5. Haustoria - hyphae of parasitic fungi which enter the
host's cells to obtain nutrition directly from the
cytoplasm
6. Mycelia - masses of intertwined hyphae; forms the main
body of a fungus
mycologists - scientists who study fungi
True fungi have cell walls composed of chitin (KY tin) - a hard
substance also found in the exoskeletons of insects and
crabs.
Most are colonial
They lack specialized structures for digestion - external
digestion
Most common type of reproduction: Asexual
Asexual reproduction: spores - most common asexual method
fragmentation
by stolons
spores form: either within an enclosure (Sporangium - where
spores are made); the whole structure is called a
sporangiophore (see page 301)
or not within an enclosure (Conidia - where
spores are made); the whole structure is called a
conidiophore (ko NID ee uh for)
Sexual reproduction: see page 302
Hyphae (haploid) of two different mycelia come in contact,
resulting in a diploid zygote. This forms a zygospore or forms a
new mycelium which grows and becomes highly specialized fruiting
body which produces and dispenses spores.
Classification in Phylum Eumycophyta
perfect fungi - those which reproduce sexually
imperfect fungi - those which do not reproduce sexually
(1)
Class Phycomycetes (a perfect fungus)
contains many of the common molds
Rhizopus nigricans - most common type of bread mold
Its sporangium disperses tiny black spores
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Not all molds which grow on foods spoil the food; some
actually make them more tasty. For example, restaurants
sometimes keep choice beefsteaks in a cooler where it is
too cold for bacteria to grow but not too cold for a
certain
type of green mold to grow. The rhizoids of this mold grow
slowly through the meat. The mold actually digests the
meat for its own use. Later, when the green mold is
scraped off and the meat is cooked, the steak is very
tender and flavorful.
Cheese molds: Cheese is formed by bacteria and molds.
The bacteria help separate the solid, white curd from the
watery whey of milk. After this separation is complete,
mold spores are introduced into the curd and the molds are
allowed to grow. The type of cheese that is formed depends
on the kind of mold spores used, the rapidity with which
the mold is allowed to grow, and the kind of milk curd
used. Roquefort cheese is made from sheep's milk and a
dark green type of mold; this famous French cheese was
originally produced in cool caves where the mold grew very
slowly. The pungent cheese known as Limburger is allowed
to mold rapidly under warm and very humid conditions.
Parasitic molds: cause serious problems for man
because they feed on important foods.
Examples:
late blight fungus of potatoes - the potato
blight of 1845 caused the starvation of approx.
250,000 people in Ireland;
also affects tomatoes - in 1946 the tomato
crop in the eastern U.S. was cut by half (est.
loss of 50 million dollars)
downy mildews - damages cabbage lettuce,
cucumbers, spinach, beans, peas, and grapes
Aquatic molds: often produce motile gametes
cause a cottony growth on dead fish
(2)
Class Ascomycetes (a perfect fungus)
"sac fungi"
sexually produce spores called ascospores inside a sac
called an ascus
asexually - conidia
Examples: molds of the genus Penicillium
antibiotic
flavors of Roquefort (Penicillium roqueforti)
and Camembert cheese
red bread mold (Aspergillus & Neurospora)
cause plant diseases (ergot of rye, chestnut
blight, & the Dutch elm disease)
powdery mildews (cobwebby mycelia on leaves &
stems of lilacs, grapes, roses, apples, and
squash)
morel - delicately flavored; the cup fungi (see
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page 304); form a saucer or bowl-shaped
fruiting body
yeasts - small, colorless, unicellular,
saprophytic mostly (some parasites); feeds
on foods containing sugar, converting the
sugar into alcohol and C02 in the process.
yeasts reproduce asexually by budding
(3)
Class Basidiomycetes (a perfect fungus)
"club fungi"
produce spores in the club-shaped basidium; spores are
called basidiospores
most are saprophytes
Examples: Mushroom
see page 306; know its structure (gills, cap,
stipe = fruiting body)
Shelf fungi
no gills - spores fall from holes on
undersurface of fruiting body
Rusts
named for the rusty-colored spores that they
leave on their hosts (such as wheat, oats,
raspberries, melons, apple trees and
evergreen trees); they are alternate
parasites: means they must have two hosts
in order to complete their life cycle (one
is harmed and the other is not)
Smuts
produce masses of black spores on their
hosts;
attack grains (corn, oats, wheat, rye,
barley); hyphae penetrate tissues of hosts
and rob them of nourishment (can't grow);
often destroy flowers so no grains are
produced
(4)
Class Deuteromycetes (imperfect fungi)
no sexual reproduction
saprophytes
plant parasites early blight of potatoes & tomatoes; apple pink rot;
peach scab, and onion white rot
human parasites ringworm, athlete's foot, thrush: a parasite of the
mucous membranes of the mouth, nose and throat
Phylum Myxomycophyta
slime molds (plasmodium)
see page 308
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fan-shaped network of veinlike branches
small group of unusual organisms - includes some yeasts
normally found in moist habitats - sometimes on rotting
logs, damp soil, and decaying organic material
The Lichens
lichens - a group of dual organisms (composed of both fungi and
algae). The algae is surrounded by mycelium of the fungus,
which provides the algae with a secure environment. Fungus
provides the water and minerals; supports and protects the
algae. The algae contains chlorophyll and is its food
maker.
Example of symbiosis:
mutualism:
two different kinds of organisms living
together
when both benefit and neither is harmed.
(see page 309)
3 general categories of lichen (based on their appearance)
1) Crustose (KRUS TOCE)- crust-like; appear as flat or nearly
flat smears of dried paint.
2) Foliose (FO lee oce)- leaf-like; small, crinkly leaves.
3) Fruticose (FR00 tih KOCE)- shrubby; have stalks or
branches.