Unit 6 Microorganisms & Fungi Ch. 20 Protists. What Is a Protist? Protist - any organism that is not a plant, an animal, a fungus, or a prokaryote Protists

Unit 6 Microorganisms & Fungi

Ch. 20 Protists

What Is a Protist?

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

Protists are eukaryotes that are not members of the kingdoms Plantae, Animalia, or Fungi

What Is a Protist?

Protists are a diverse group of mainly single-celled eukarytoes

Animallike Protists: Protozoans

Zooflagellates - animallike protists that swim using flagella

Most reproduce asexually resulting in 2 genetically identical cells


Sarcodines - animallike protists that use pseudopods for feeding & movement

Pseudopods - temporary cytoplasmic projections


Amoeboid movement - when the cytoplasm of the cell streams into the pseudopod, & the rest of the cell follows

Food vacuole - a small cavity in the cytoplasm that temporarily stores food


Ciliates - use cilia for feeding & movement Cilia - short, hairlike projections similar to

flagella


- Trichocysts - small, bottle-shaped structures used for defense

Macronucleus - a genetic “library”, where multiple copies of most of the genes the cell needs in its day-to-day existence are kept

Micronucleus - a “reserve copy” of all of the cell’s genes


Gullet - an indentation in 1 side of the organism, where trapped food moves into the food vacuoles

Anal pore - when waste materials are emptied into the environ.

Contractile vacuole - cavities in the cytoplasm that collect water


Sporozoans - do not move on their own, & are parasitic

Animallike Protists & Disease

Some animallike protists cause serious diseases, including malaria & African Sleeping Sickness

Malaria

1 of the world’s most serious infectious diseases As many as 2 million people die from malaria

every year Its caused by the sporozoan Plasmodium,

& carried by the female Anopheles mosquito

Ecology of Animallike Protists

Many animallike protists play essential roles in the living world

Some are beneficial to other organisms Ex.) Termites

Plantlike Protists: Unicellular Algae

Many protists contain chlorophyll & carry out photosynthesis


Accessory pigments - compounds in algae that absorb light

Chlorophyll & accessory pigments allow algae to harvest & use the energy from sunlight


Euglenophytes - plantlike protists that have 2 flagella but no cell wall

Eyespot - cluster of reddish pigment, that helps the organism find sunlight to power photosynthesis

Pellicle - intricate cell membrane


Chrysophytes - diverse group of plantlike protists that have gold-colored chloroplasts


Diatoms - produce thin, delicate cell walls rich in silicon, the main component of glass


Dinoflagellates - generally have 2 flagella, half are photosynthetic & the other half are heterotrophs

Ecology of Unicellular Algae

Phytoplankton - the small, photosynthetic organisms found near the surface of the ocean

About 1/2 of the photosynthesis that occurs on Earth is carried out by phytoplankton

Ecology of Unicellular Algae

Many protists grow rapidly in regions where sewage is discharged, causing an algal bloom

These algal blooms deplete the water of nutrients, & the cells die in great numbers

Plantlike Protists: Red, Brown, & Green Algae Red algae - able to live at great depths due to their

efficiency in harvesting light energy Red algae contain chlorophyll a & reddish

accessory pigments called phycobilins Phycobilins - good at absorbing blue

light, enabling red algae to live deeper in the ocean than many other photosynthetic algae

Plantlike Protists: Red, Brown, & Green Algae Brown algae - contain chlorophyll a & c, as well

as a brown accessory pigment, fucoxanthin

Plantlike Protists: Red, Brown, & Green Algae Green algae - share many

characteristics with plants, including their photosynthetic pigments & cell wall composition

Human Uses of Algae

Algae produce much of earth’s oxygen through photosynthesis

Many species are rich in vitamin C & iron Chemicals in algae are used to treat

stomach ulcers, high blood pressure, arthritis, & other health problems

Funguslike Protists

Like fungi, the funguslike protists are heterotrophs that absorb nutrients from dead or decaying organic matter

But unlike most true fungi, funguslike protists have centrioles

They also lack the chitin cell walls of true fungi

Funguslike Protists

Slime molds - funguslike protists that play key roles in recycling organic material

Cellular slime molds - individual cells Acellular slime molds - cells fuse to form large

cells with many nuclei

Funguslike Protists

Water molds - (oomycetes) - thrive on dead or decaying organic matter in water & some are plant parasites on land

Funguslike Protists

An oomycete that produced airborne spores that destroy all or parts of the potato plant, caused the potato famine in Ireland, in the 1840s

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Unit 6 Microorganisms & Fungi Ch. 20 Protists. What Is a Protist? Protist - any organism that is not a plant, an animal, a fungus, or a prokaryote Protists