The Kingdom Protista

What Is a Protist?

• Classification of Protists• One way protists can be classified is by how they

obtain nutrition: – Heterotrophs are called animal-like protists. – Photosynthesizers are called plantlike protists. – Decomposers and parasites are called funguslike protists.

Animal-like Protists: Protozoans

20-2 Animal-like Protists:

• There are four phyla of animal-like protists:• zooflagellates• sarcodines• ciliates• sporozoans

– Animal-like protists are classified by their means of movement.

Zooflagellates

• Zooflagellates– What are the distinguishing features of the

zooflagellates?

Sarcodines

• Sarcodines– What are the distinguishing features of the

sarcodines?

Sarcodines

• Amoebas

• Amoebas are flexible, active cells with thick pseudopods that extend out of the central mass of the cell.

• Cytoplasm streams into the pseudopod, and the rest of the cell follows.

• This type of locomotion is known as amoeboid movement.

Nucleus

Food vacuole

Contractile vacuole

Pseudopods

Structures of an Amoeba

Sarcodines

• Amoebas reproduce by mitosis and cytokinesis.

Ciliates

• Ciliates– What are the distinguishing features of

the ciliates?

Ciliates• Structures of a Paramecium

Ciliates

• Paramecia possess two types of nuclei:

• The macronucleus keeps multiple copies of most genes that the cell needs in its day-to-day existence.

• The micronucleus contains a copy of all of the cell's genes.

Sporozoans

• Sporozoans– What are the distinguishing features of the

sporozoans?

Sporozoans

• Many sporozoans have complex life cycles that involve more than one host.

• Sporozoans reproduce by sporozoites.

• A sporozoite can attach itself to a host cell, penetrate it, and then live within it as a parasite.

Animal-like Protists and Disease

• Animal-like Protists and Disease– How do animal-like protists harm other living

things?

Animal-like Protists and Disease• Malarial Infection

Animal-like Protists and Disease• A female Anopheles mosquito bites a human

infected with malaria and picks up Plasmodium gamete cells.

Animal-like Protists and Disease• The sexual phase of the Plasmodium life

cycle takes place inside the mosquito.

Animal-like Protists and Disease• Gametes fuse to form zygotes, meioses

occurs, and sporozoites are produced and migrate to salivary gland.

• Infected mosquito bites another human, injecting saliva that contains Plasmodium sporozoites.

Animal-like Protists and Disease

Plasmodium sporozoites

• Sporozoites infect liver cells and multiply asexually.

Animal-like Protists and Disease

Liver

Plasmodium sporozoites

• Infected liver cells burst, releasing Plasmodium cells called merozoites that infect red blood cells.

Animal-like Protists and Disease

Plasmodium sporozoites

Liver

Liver cells burst

Merozoites

Animal-like Protists and Disease

Red blood cells

Merozoites

•Merozoites reproduce asexually inside red blood cells.

Animal-like Protists and Disease•Infected red blood cells burst, releasing merozoites that infect other red blood cells. Some cells release gametes that can infect mosquitoes.

Red blood cells

Merozoites

Plantlike Protists: Unicellular Algae

• Plantlike protists contain chlorophyll and carry out photosynthesis.

• Plantlike protists are commonly called “algae.”

• Algae are sometimes classified with the plants.

Plantlike Protists

• The four phyla of unicellular algae are:• euglenophytes• chrysophytes• diatoms• dinoflagellates

Plantlike Protists

Euglenophytes

• Euglenophytes– What are the distinguishing features of the

euglenophytes?

Euglenophytes

Gullet

Flagella

Eyespot

Pellicle

Contractile vacuoleCarbohydratestorage bodies

Chloroplast

Nucleus

• Near the gullet is a reddish pigment known as the eyespot, which helps find sunlight to power photosynthesis.

• Euglenas can also live as heterotrophs.

Euglenophytes

Eyespot

• Euglenas do not have cell walls. Instead, they have an intricate cell membrane called a pellicle.

• The pellicle folds into ridges, each supported by microtubules.

EuglenophytesPellicle

Euglenophytes

• Euglenas reproduce asexually by binary fission.

Chrysophytes

• Chrysophytes– What are the distinguishing features of

the chrysophytes?

Chrysophytes

• The cell walls of some chrysophytes contain the carbohydrate pectin rather than cellulose, and others contain both.

• Chrysophytes store food in the form of oil rather than starch.

• They reproduce both asexually and sexually.

• Most are solitary, but some form threadlike colonies.

Diatoms

• Diatoms– What are the distinguishing features of

the diatoms?

Dinoflagellates

• Dinoflagellates– What are the distinguishing features of

the dinoflagellates?

Dinoflagellates

• Dinoflagellates have two flagella that fit in grooves between two thick plates of cellulose that protect the cell.

• Most dinoflagellates reproduce asexually by binary fission.

• Many dinoflagellates are luminescent. When they are agitated, they give off light.

Plantlike Protists: Red, Brown, and Green Algae

Plantlike Protists: Red, Brown, and Green Algae

• The three phyla of algae that are largely multicellular are:

• red algae• brown algae• green algae

Red Algae

• Red Algae– What are the distinguishing features of red

algae?

Brown Algae

• Brown Algae– What are the distinguishing features of brown

algae?

Brown Algae

• Brown Alga StructureBlades

Bladder

Stipe

Holdfast

Green Algae

• Green Algae– What are the distinguishing features of green

algae?

Funguslike Protists

– What are the similarities and differences between funguslike protists and fungi?

• Slime Molds– What are the defining characteristics of the

slime molds?

Slime Molds

Slime Molds

• Two groups of slime molds are recognized:

• Cellular slime molds, whose individual cells remain separated during every phase of the mold's life cycle.

• Acellular slime molds, which pass through a stage in which its cells fuse to form large cells with many nuclei.

Slime Molds

– Cellular Slime Molds • Most cellular slime molds live as free-living cells

that are not easily distinguishable from soil amoebas.

• In nutrient-rich soils, these amoeboid cells reproduce sexually and produce diploid zygotes.

Slime Molds•Life Cycle of a Cellular Slime Mold

Fruiting body Spores

Emergingamoebas

Fruiting body

Aggregatedamoebas

Migrating colony

Solitary cell

Zygote

Slime Molds

• When food is scarce, the cells produce spores.

• They emit chemicals to attract cells of the same species.

• Cells gather into a colony that functions like one organism.

Slime Molds

• The colony moves slightly, then stops to produce a fruiting body, a slender reproductive structure that produces spores.

• Then the spores are scattered from the fruiting body.

• Each spore produces one cell, starting the cycle again.

Slime Molds

– Acellular Slime Molds • Acellular slime molds begin as amoeba-like cells. • When they aggregate, their cells fuse to produce

structures with many nuclei known as plasmodia.

Slime Molds

•Life Cycle of an Acellular Slime Mold

Spores Germinating

Maturesporangium Young

sporangiumMature

plasmodium

Feedingplasmodium

Zygote

Fertilization

Water Molds

• Water Molds– What are the defining characteristics of the

water molds?

Water Molds

FERTILIZATION

MEIOSISSEXUAL

REPRODUCTION

ASEXUAL REPRODUCTION