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