Protists Chapter 25 Table of Contents Section 1 Characteristics of Protists Section 2 Animal-like Protists Section 3 Plantlike and Funguslike Protists

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.


Chapter 25

Click below to watch the Visual Concept.

Visual Concept

Characteristics of Protists


Chapter 25

A Diverse Group of Eukaryotes, continued

• The First Eukaryotes– Evidence suggests that the first protists arose

from endosymbiotic prokaryotes.


Chapter 25


Visual Concept

Origin of Eukaryotic Cells


Chapter 25

Classification

• Protists are classified by the characteristics that make them fungus-like, plant-like, or animal-like.


Chapter 25

Characteristics

• Unicellular and Multicellular– Most protists are unicellular, but some form large,

multicellular bodies.


Chapter 25


Visual Concept

Comparing Organisms that are Unicellular and Multicellular


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.


Chapter 25

Characteristics, continued

• Motility– Protists use flagella, cilia, or pseudopodia for

locomotion.


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 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.


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.


Phylum Protozoa, continued

• Protozoan Diversity– Protozoans include organisms that inhabit the

oceans, lakes, soil and even the human intestines.


Phylum Ciliophora

• Animal-like protists include the phylum Ciliophora.

• Ciliates move using cilia, which are short, hairlike, cytoplasmic projections that line the cell membrane.


Phylum Ciliophora, continued

• Characteristics– Ciliates have the most elaborate organelles,

including two types of nuclei.

Chapter 25


Visual Concept

Feeding Habits of a Ciliate



Phylum Ciliophora, continued

• Reproduction– Ciliates reproduce asexually by binary fission and

sexually by conjugation.


Phylum Sarcomastigophora

• Animal-like protists include the phyla Protozoa, Sarcomastigophora.

• For locomotion, sarcomastigophorans use flagella.


Phylum Apicomplexa

• Animal-like protists include the phyla Apicomplexa.

• These protists are animal parasites.

Chapter 25


Visual Concept

Types of 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.


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.


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.


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.



• 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.



• Phylum Bacillariophyta (Diatoms)– The phylum Bacillariophyta contains as many as

100,000 species of unicellular protists called diatoms.



• 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.



• 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.



• 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.

Chapter 25Section 3 Plantlike and Funguslike Protists

Structure of Euglena


Funguslike Protists

• Biologists recognize two groups of funguslike protists: slime molds and water molds.


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.



• 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.



• Phylum Oomycota (Water Molds)– Water molds are composed of branching filaments

and many of this phylum are parasitic.



• 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.


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.


Protists in the Environment, continued

• Ecology of Protists– Algal blooms can lead to the depletion of oxygen

in water. – Red tides produce harmful toxins.


Protists in Research

• Research on protists has helped biologists understand a number of fundamental cellular functions, such as leukocyte movement.


Protists in Industry

• Protists as Food– For thousands of years, humans have been

collecting seaweeds for food.


Protists in Industry, continued

• Protist Byproducts– Protists provide important byproducts, such as

alginate, carrageenan, and agar.


Protists and Health

• Parasitic protists cause malaria, giardiasis, cryptosporidiosis, and trichomoniasis in humans.


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.

Chapter 25

Life Cycle of Plasmodium


Chapter 25


Visual Concept

Malaria Life Cycle


Documents

Protists Chapter 25 Table of Contents Section 1 Characteristics of Protists Section 2 Animal-like Protists Section 3 Plantlike and Funguslike Protists