plantlike& funguslike protists sections 20-3, 20-4,...
TRANSCRIPT
Plantlike& Funguslike Protists
Sections 20-3, 20-4, 20-5
Plantlike Protists: Unicellular Algae
Section 20-3 Characteristics of Algae:
• Plantlike members of the kingdom
Protista
• Eukaryotes
• Autotrophic – contain chlorophyll &
make food by photosynthesis
• Range in size from microscopic to
seaweeds hundreds of feet in length
• Do not have true roots, stems, or leaves
• Produce oxygen that is returned to the
atmosphere
• Found in freshwater, marine, and moist
soil habitats
• Most have flagella at some time in life
cycle
• Algae cells contain organelles called
pyrenoids organelles that make & store
starch
Classification:
• Classified into 7 phyla based on:
-color
-type of chlorophyll
-form of food-storage substance
-cell wall composition
• All phyla contain chlorophyll a
• All algae live in water or moist areas (ponds, seas, moist soil, ice...)
• Act as producers making food & oxygen
Chrysophyta (golden algae)
or (yellow-green algae)
• Most live in freshwater habitats, but some are marine
• Unicellular algae containing chlorophyll a & c and the brown pigment fucoxanthin and carotenoids
• Cell walls contain pectin rather than cellulose
• Store food in the form of oil rather than
starch
• May form highly resistant cysts to
survive beneath frozen lake surfaces in
winter
Bacillariophyta (diatoms):
• Abundant in marine & freshwater habitats
• Called phytoplankton & start many aquatic food chains
• Contain chlorophyll a & c, carotenoids (orange pigments), & xanthophyll (yellow pigments)
• Store food as starch & contain mainly cellulose in their cell walls
• Lack cilia & flagella
• Have glass like shells containing
silicon that fit together in 2 parts
• Centric diatoms are
marine & have circular
or triangular shells
• Pennate diatoms are found in freshwater & have rectangular shells
• When diatoms die, they form a layer
called diatomaceous earth that is
abrasive and used in detergents,
toothpaste, fertilizers, etc.
Dinoflagellata or Pyrrophyta
(dinoflagellates):
• Major producers in marine habitats
• Small, unicellular organisms making
up plankton
• Many are photosynthetic, but some are
colorless heterotrophs
• Photosynthetic
dinoflagellates are
yellow to brown in
color due to
chlorophyll a & c
and carotenoids
• Have 2 flagella
that spin and
move the
dinoflagellate
through water
• Store food as
starch
• Some are covered
with armor like
plates & spines
made of cellulose
• Often undergo
algal blooms
where their
numbers greatly
increase
• Produce a toxic
substance and
cause poisonous
red tides
• Some such as Noctiluca can
produce light by bioluminescence
Section 20-4: Plantlike Protists
Rhodophyta (red algae)
• Multicellular algae that mainly grow deep in warm marine waters to polar regions
• Contain chlorophyll a & phycobilins (red pigments) to trap sunlight for photosynthesis
• Store food as starch
• Cell walls contain cellulose and agar
(used as a base in culture dishes to
grow microbes)
• Some species contain carageenan in
their cell walls used for gelatin
capsules & in some cheeses
Polysiphonia
(red algae)
• Important role in the formation of coral
reefs
– provide nourishment for coral animals
Phaeophyta (brown algae):
• Contain chlorophyll a & chlorophyll c
and fucoxanthin (brown pigment) as
accessory pigments
• Most are multicellular growing in cooler
marine habitats
• Include kelps & seaweeds
• Largest protists
• Specialized rootlike
holdfasts anchor
thallus to rocks
• Specialized air
bladders keep
leaflike blades afloat
near surface to get
light for
photosynthesis
• Stemlike structures
are called the stipe
and support the
blades
• Store food as a carbohydrate called
laminarin
• Sargassum forms huge floating mats
many kilometers long in the Atlantic
Ocean
• Fucus or
rockweed
attaches to the
bottom by a
holdfast.
• Macrocystis or
giant kelp
contains algin in
its cell walls
which is used in
cosmetics, some
drugs, ice cream,
etc.
Chlorophyta (green algae):
• Contain chlorophyll a & chlorophyll b
and carotenoids (orange & yellow
pigments) as accessory pigments
• Store food as starch
• Cell walls mainly cellulose, but some
marine forms add CaCO3
3 Types include:
1. Unicellular algae are single-celled
& make up phytoplankton (a
population of photosynthetic
organisms that begins many aquatic
food chains)
• Phytoplankton make most of the
world's carbohydrates and are the
major producers of oxygen
Unicellular Green Algae
• Chlamydomonas
which is a single
celled green algae
growing in ponds,
ditches and wet
soil.
–The body of
algae is called
the thallus.
2. Colonial algae
consist of groups of
cells working
together.
• Some colonial
algal cells may
specialize for
movement,
feeding, or
reproduction
showing for
division of labor.
• Filamentous algae
have slender,
rod-shaped thallus
arranged in rows
joined end-to-end
• Holdfasts are
specialized
structures in some
filamentous algae
that attaches the
algae so it can grow
toward sunlight at
the surface
Colonial Green Algae
• Spirogyra
(freshwater)
forms long
thread like
colonies called
filaments
resembling cells
that are stacked
like aluminum
cans placed end
to end.
Volvox consists of as few as 500 to as
many as 50,000 cells arranged to form
hollow spheres.
3. Multicellular
algae often have a
large, complex leaf-
like thallus & may
have stem-like
sections and air
bladders
• Macrocystis is
among the largest
multicellular algae
Multicellular Green Algae
• Ulva or "sea lettuce" is a bright-green
marine alga that is commonly found
along rocky seacoasts.
Human Uses of Algae
• Major food source for life in the ocean
• Brown kelp forests are home to many
animal species
• Rich in vitamin C and iron
• Used to treat stomach ulcers, high
blood pressure, arthritis
• Used to make plastics waxes,
deodorants, paints, lubricants.
• Agar, thickens the nutrient mixtures
used to grow bacteria.
• Used in food products such as ice
cream, salad dressing, pudding, candy
bars, pancake syrup and eggnog
• Red algae Porphyra, called nori in
Japanese, is used to wrap rice,
fish and vegetables to
make sushi.
Sec. 20-5 Funguslike Protists
Characteristics of Fungal Protists:
• Includes cellular slime molds, plasmodial slime molds, & water molds
• Unique life cycles with two phases
• Multicellular, heterotrophic organisms
• Small & live in moist or watery habitats
• Act as decomposers breaking down dead organic matter
Slime molds
• Shiny, wet appearance
• Often brightly colored (yellow or
orange)
• Life cycles with 2 phases --- a mobile
feeding stage & a nonmotile
reproductive stage
• Fungal-like in
nutrition
(absorptive
heterotrophs that
break down dead
organic matter)
• May be
saprophytes or
parasites
• Multinucleate body mass
• May have a mobile, ameoba-
like feeding stage
• Make a reproductive structure
or fruiting body that produces
spores
• Often found on decaying wood
or leaves
A is Lycogala epidendrum, B is Comatricha typhoides,
C is Badhamia utricularia, D is Dictydium
• Two groups of slime molds:
• Cellular Slime Molds (Phylum
Acrasiomycota)
• Acellular Slime Molds (Phylum
Myxomycota)
Acrasiomycota (Cellular
Slime Molds) • Alternate in their life cycle between
amoeboid feeding stage & spore-producing
fruiting body
• Live in freshwater, moist soil
• Clump together into masses called
pseudoplasmodium whenever little
food is available
• Cells in the pseudoplasmodium
are independent but move
together "slug-like"
• Pseudoplasmodium settles &
forms fruiting body with spores
• Spores spread by wind to new
location & form individual
amoeboid feeding stage
Myxomycota (Plasmodial
Slime Molds) • Exist as a plasmodium ( a mass of
cytoplasm with many nuclei)
• Plasmodium creeps along over
decaying material
• Decomposes & absorbs plant
material as food
• When food is scarce, the
plasmodium forms stalked fruiting
bodies with spores that are
resistant to bad environmental
conditions
• When conditions turn favorable,
spores form a new plasmodium
Oomycota (Water Molds)
• Fungal-like organism made of
branching filaments with cell walls of
cellulose
• Aquatic water molds are parasites on
fish forming furry growths on their gills
• May act as decomposers in water of
dead plants & animals
• May be pathogenic to plants
e.g. Phytophthora infestans caused
blight in potatoes (Irish Potato Famine
in 19th century)
• Blight in plants decays & discolors
stems & leaves