ProtistsChapter 25
Table of Contents
Section 1 Characteristics of Protists
Section 2 Animal-like Protists
Section 3 Plantlike and Funguslike Protists
Section 4 Protists and Humans
Section 1 Characteristics of ProtistsChapter 25
Objectives
• Define protist.
• Describe a hypothesis for the origin of eukaryotic cells.
• Explain how protists are classified.
• Describe the two major ways by which protists obtain energy.
• List three structures protists use for movement.
• Describe how protists reproduce.
Chapter 25
A Diverse Group of Eukaryotes
• Protists are unicellular or simple multicellular eukaryotic organisms that are not plants, fungi, or animals.
Section 1 Characteristics of Protists
Chapter 25
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Visual Concept
Characteristics of Protists
Section 1 Characteristics of Protists
Chapter 25
A Diverse Group of Eukaryotes, continued
• The First Eukaryotes– Evidence suggests that the first protists arose
from endosymbiotic prokaryotes.
Section 1 Characteristics of Protists
Chapter 25
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Visual Concept
Origin of Eukaryotic Cells
Section 1 Characteristics of Protists
Chapter 25
Classification
• Protists are classified by the characteristics that make them fungus-like, plant-like, or animal-like.
Section 1 Characteristics of Protists
Chapter 25
Characteristics
• Unicellular and Multicellular– Most protists are unicellular, but some form large,
multicellular bodies.
Section 1 Characteristics of Protists
Chapter 25
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Visual Concept
Comparing Organisms that are Unicellular and Multicellular
Section 1 Characteristics of Protists
Chapter 25
Characteristics, continued
• Nutrition– Many protists are autotrophs, organisms that
make their own food. – Other protists are heterotrophs, organisms that
must get their food by eating other organisms or their byproducts.
Section 1 Characteristics of Protists
Chapter 25
Characteristics, continued
• Motility– Protists use flagella, cilia, or pseudopodia for
locomotion.
Section 1 Characteristics of Protists
Chapter 25
Reproduction
• Protists reproduce either asexually, sexually, or both.
• They reproduce asexually by binary fission or multiple fission.
• They often reproduce sexually by conjugation.
Section 1 Characteristics of Protists
Section 2 Animal-like ProtistsChapter 25
Objectives
• Discuss the key characteristics of Protozoa, Ciliophora, Sarcomastigophora, and Apicomplexa.
• Describe how protozoa use pseudopodia to move and to capture food.
• Explain how ciliates move and reproduce.
• Describe how mastigophorans move and capture food.
• Describe the role of apicomplexans in disease.
Section 2 Animal-like ProtistsChapter 25
Phylum Protozoa
• Animal-like protists can be found in the phylum Protozoa.
• Protozoa use large, rounded, cytoplasmic extensions called pseudopodia for both movement and feeding.
Section 2 Animal-like ProtistsChapter 25
Phylum Protozoa, continued
• Protozoan Diversity– Protozoans include organisms that inhabit the
oceans, lakes, soil and even the human intestines.
Section 2 Animal-like ProtistsChapter 25
Phylum Ciliophora
• Animal-like protists include the phylum Ciliophora.
• Ciliates move using cilia, which are short, hairlike, cytoplasmic projections that line the cell membrane.
Section 2 Animal-like ProtistsChapter 25
Phylum Ciliophora, continued
• Characteristics– Ciliates have the most elaborate organelles,
including two types of nuclei.
Chapter 25
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Visual Concept
Feeding Habits of a Ciliate
Section 2 Animal-like Protists
Section 2 Animal-like ProtistsChapter 25
Phylum Ciliophora, continued
• Reproduction– Ciliates reproduce asexually by binary fission and
sexually by conjugation.
Section 2 Animal-like ProtistsChapter 25
Phylum Sarcomastigophora
• Animal-like protists include the phyla Protozoa, Sarcomastigophora.
• For locomotion, sarcomastigophorans use flagella.
Section 2 Animal-like ProtistsChapter 25
Phylum Apicomplexa
• Animal-like protists include the phyla Apicomplexa.
• These protists are animal parasites.
Chapter 25
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Visual Concept
Types of Animal-like Protists
Section 2 Animal-like Protists
Section 3 Plantlike and Funguslike ProtistsChapter 25
Objectives
• Describe four main body forms of algae.
• List the common name for each of the seven phyla of plantlike protists.
• Explain how green algae and plants are similar.
• Describe four phyla of funguslike protists.
• Compare plasmodial slime molds, cellular slime molds, and water molds.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Characteristics of Algae
• Algae can be unicellular, colonial, filamentous, or multicellular.
• Seven phyla of plantlike protists are Chlorophyta, Phaeophyta, Rhodophyta, Bacillariophyta, Dinoflagellata, Chrysophyta, and Euglenophyta.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Plantlike Protists
• Phylum Chlorophyta (Green Algae)– The phylum Chlorophyta contains more than
17,000 identified species of protists called green algae.
– Both green algae and plants have chlorophylls and accessory pigments, store food as starch, and have cell walls made up of cellulose.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Plantlike Protists, continued
• Phylum Phaeophyta (Brown Algae)– The phylum Phaeophyta includes approximately
1,500 species of multicellular organisms called brown algae.
– Brown algae are mostly marine organisms, and they include plantlike seaweeds and kelps.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Plantlike Protists, continued
• Phylum Rhodophyta (Red Algae)– The 4,000 species in the phylum Rhodophyta are
known as red algae. – A few species of red algae live in fresh water or on
land, but most red algae are marine seaweeds.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Plantlike Protists, continued
• Phylum Bacillariophyta (Diatoms)– The phylum Bacillariophyta contains as many as
100,000 species of unicellular protists called diatoms.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Plantlike Protists, continued
• Phylum Dinoflagellata (Dinoflagellates)– More than 2,000 species of organisms called
dinoflagellates make up the phylum Dinoflagellata.– Some species of dinoflagellates, such as those in
genus Noctiluca, can produce bioluminescence, a display of sparkling light often seen in ocean water at night.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Plantlike Protists, continued
• Phylum Chrysophyta (Golden Algae)– The phylum Chrysophyta contains about 1,000
species of golden algae. Most golden algae live in fresh water, but a few species are found in marine environments.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Plantlike Protists, continued
• Phylum Euglenophyta (Euglenoids)– The phylum Euglenophyta contains about 1,000
species of flagellated unicellular algae called euglenoids.
– Euglenoids are both plantlike and animal-like. Many are autotrophic, like plants, but they lack a cell wall and are highly motile, like animals.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Funguslike Protists
• Biologists recognize two groups of funguslike protists: slime molds and water molds.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Funguslike Protists, continued
• Phylum Myxomycota (Plasmodial Slime Molds)– Plasmodial slime molds are multinucleate.– As the plasmodium creeps along the forest floor
by cytoplasmic streaming, it consumes decaying leaves and other debris by phagocytosis.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Funguslike Protists, continued
• Phylum Dictyostelida (Cellular Slime Mold)– Cellular slime molds live as individual haploid
cells that move about like amoebas. – Each cell moves as an independent organism,
creeping over the ground or swimming in fresh water and ingesting food.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Funguslike Protists, continued
• Phylum Oomycota (Water Molds)– Water molds are composed of branching filaments
and many of this phylum are parasitic.
Section 3 Plantlike and Funguslike ProtistsChapter 25
Funguslike Protists, continued
• Phylum Chytridiomycota (Water Molds)– Members of phylum Chytridiomycota, or the
chytrids, are primarily aquatic protists characterized by gametes and zoospores with a single, posterior flagellum.
Section 4 Protists and HumansChapter 25
Objectives
• State four environmental roles of protists.
• Describe algal blooms and red tides and their impact.
• State an important role for protists in research.
• List a use of protists as food and three uses of protist byproducts.
• Describe four protist-caused diseases.
Section 4 Protists and HumansChapter 25
Protists in the Environment
• Protists produce large amounts of oxygen, form the foundation of food webs, recycle materials, and play a role in several symbiotic relationships.
Section 4 Protists and HumansChapter 25
Protists in the Environment, continued
• Ecology of Protists– Algal blooms can lead to the depletion of oxygen
in water. – Red tides produce harmful toxins.
Section 4 Protists and HumansChapter 25
Protists in Research
• Research on protists has helped biologists understand a number of fundamental cellular functions, such as leukocyte movement.
Section 4 Protists and HumansChapter 25
Protists in Industry
• Protists as Food– For thousands of years, humans have been
collecting seaweeds for food.
Section 4 Protists and HumansChapter 25
Protists in Industry, continued
• Protist Byproducts– Protists provide important byproducts, such as
alginate, carrageenan, and agar.
Section 4 Protists and HumansChapter 25
Protists and Health
• Parasitic protists cause malaria, giardiasis, cryptosporidiosis, and trichomoniasis in humans.
Section 4 Protists and HumansChapter 25
Protists and Health
• Malaria– Parasitic protists in the genus Plasmodium cause
malaria, which is characterized by severe chills, headache, fever, and fatigue.
– Each year, nearly 3 million people die from malaria.