chapter 20: protists biology- kirby. 20-1: the kingdom protista protist- any organism that is not a...

Chapter 20: ProtistsBiology- Kirby

20-1: The Kingdom Protista

• Protist- any organism that is not a plant, animal, fungus, or prokaryote.

• Protists are eukaryotes, and most are unicellular.

• The first eukaryotic organisms on Earth were protists (1.5 billion years ago).

20-1: The Kingdom Protista

• 3 types of protists:–Animallike- heterotrophs–Plantlike- autotrophs–Funguslike- external digestion

such as decomposers or parasites.

20-2: Animallike Protists: Protozoans

• There are 4 types of protozoans classified by their movement:–Zooflagellates–Sarcodines–Ciliates–Sporozoans


• Zooflagellates- move through aquatic environments with flagella.

• They can have more than 1 flagella.• Able to absorb food through cell

membrane.• Most reproduce asexually by

mitosis and cytokinesis.• Some reproduce sexually by

meiosis and the formation of gametes.


• Sarcodines- use pseudopods for feeding and movement.

• Pseupod- “false foot”• Example: Amoeba- capture and

digest food by forming a food vacuole with its cytoplasm.

• They reproduce by mitosis and cytokinesis.


• Ciliates- use cilia for feeding and movement.

• Cilia- short hairlike projections similar to flagella. Cilia move together, or beat, and move the organism very quickly.

• Example: Paramecium- have a macronucleus and a micronucleus.

• Cilia sweep food into the gullet.


• Continued:

•Waste exit through an anal pore in the membrane.

• A cavity called contractile vacuole holds and expels water.

• Usually reproduce asexually by mitosis and cytokinesis. Under stress, paramecium undergo conjugation.


• Sporozoans- do not move on their own; parasitic.

• Attaches itself to a host and lives inside it.

• Some animallike protists cause diseases like malaria and African sleeping sickness.

• Others are beneficial to organisms.


• Zooflagellates

• Sarcodines

• Ciliates

• Sporozoans

20-3: Plantlike Protists-Unicellular Algae

• Plantlike protists are called algae.

• They contain chlorophyll which makes them appear green.

• Some scientists think algae are more closely related to plants; but we consider them to be protists.


• Accessory pigments- absorb light at different wavelengths than chlorophyll- give algae a range of color.

• There are 4 phyla of unicellular algae:– Euglenophytes– Chrysophytes– Diatoms– Dinoflagellates


• Euglenophytes:• Plantlike protists that have 2

flagella and no cell wall.• Have an eyespot which allows

the organism to find sunlight.• Can also live as heterotrophs by

absorbing nutrients.


• Chrysophytes:• Means “golden plants” because

they have gold-colored chloroplasts.

• Diatoms:• Produce thin cell walls made of

silicon which make the walls look like glass.


• Dinoflagellates:• Half are autotrophs, half are

heterotrophs.• Many are luminescent and give

off light when agitated by sudden movement in water.

20-4: Plantlike Protists-Red, Brown, & Green Algae

• There are 3 phyla of multicellular algae:–Red algae–Brown algae–Green algae

20-4: Plantlike Protists-Red, Brown, & Green Algae• Red algae:• Able to live deep in the water.• Have chlorophyll a and reddish

accessory pigments called phycobilins.

• Important to the formation of coral reefs.

20-4: Plantlike Protists-Red, Brown, & Green Algae• Brown algae:• Contain chlorophyll a and c, and a

brown accessory pigment called fucoxanthin.

• Largest and most complex of the algae.

• Live in cool, shallow waters.


• Green algae:• Contain chlorophyll a and b, and

cellulose in cell walls.• Live in fresh and salt water. • Unicellular green algae- 2 flagella &

single chloroplast.• Colonial green algae- cells are stacked.• Multicellular green algae- has

specialized cells & lives on rocky coasts.


• Green algae Reproduction:• Life cycle includes both a diploid

and haploid generation.

20-5: Funguslike Protists

• Funguslike protists are heterotrophs that absorb nutrients from dead/decaying matter.

• Slime molds- funguslike protists that recycle organic material.–Cellular slime molds- individual

cells remain separated during life cycle.

–Acellular slime molds- cells fuse to form large cells with many nuclei called plasmodia.

20-5: Funguslike Protists

• Water molds- thrive on dead/decaying matter in water & some are plant parasites on land.

• Produce thin filaments called hyphae which aid in reproduction.

• Slime and water molds are very beneficial because they help decompose matter, but some can cause plant diseases.

chapter 20: protists biology- kirby. 20-1: the kingdom protista protist- any organism that is not a...

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