Protists

Chapter 20

What are protists?

• Contains more than 200,000 species• Is any organism that is not a plant, an animal,

a fungus or a prokaryote.• Are eukaryotes• Appeared on earth about 1.5 bya

What are the distinguishing features of the major phyla of animal-like protists?

• Zooflagellates swim with flagella• Sarcodines move by extensions of their

cytoplasm• Ciliates move by means of cilia• Sporozoans do not move on their own at all

Zooflagellates• Animal like protists that swim using flagella• Absorb food through their cell membranes• Live in lakes and streams• Most reproduce asexually

Sarcodines• Animal like protist that use pseudopods for

feeding and movement• Amoeboid movement is when the cytoplasm

streams and the rest follows• Capture and digest particles of food

Ciliates• Use cilia for feeding and movement• Found in both fresh and salt water• Uses conjugation to exchange genetic

information to maintain genetic diversity• Reproduce asexually

Sporozoans• Do not move on their own and are parasitic• Have complex life cycles that involve more

than one host• Can cause serious diseases, including malaria

and African sleeping sickness

How do animal-like protists harm other living things?Maleria

Sleeping Sickness

Amebic dysentary

What is the function of chlorophyll and accessory pigments in algae?

• Allow algae to harvest and use the energy from the sunlight

• Accessory pigments are compounds that absorb light at different wavelengths

What are the distinguishing features of the major phyla of unicellular algae?

• Euglenophytes have two flagella but no cell wall

• Chrysophyta have gold-colored chroloplasts• Diatoms produce thin, delicate cell walls rich

in silicon, the main component of glass• Dinoflagellates – half are photosynthetic and

half are hetertrophs

Euglenophytes• Flagella emerge from the gullet• Have an eyespot to help find sunlight• Can be photosynthetic or heterotrophic, can

switch to meet the environment• No cell walls• Intricate cell membrane called a pellicle• Reproduce asexually

Chrysophytes• Includes yellow-green algae and golden-

brown algae• Means “golden plants”• Cell walls contain pectin• Store food as oil and not starch• Reproduce sexually and asexually

Diatoms

• Most abundant and beautiful organisms on earth

Dinoflagellates

• Have two flagella• Reproduce asexually• Are luminescent and when agitated give off

light

Summarize the ecological roles of unicellular algae.

• Make up a considerable part of phytoplankton• About ½ of the photosynthesis on Earth is

carried out by phytoplankton• Grow rapidly where sewage is discharged to

form blooms• Blooms deplete water of nutrients and oxygen• Red Tides – contains a toxin that becomes

concentrated in the tissues of clams and oysters, can cause illness, paralysis or death