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 –What are the distinguishing features of the zooflagellates?

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 –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 –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 –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 –What are the distinguishing features of the euglenophytes?

Euglenophytes Gullet Flagella Eyespot Pellicle Contractile vacuole Carbohydrate storage 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. Euglenophytes Pellicle

Euglenophytes Euglenas reproduce asexually by binary fission.

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 –What are the distinguishing features of the diatoms?

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

The three phyla of algae that are largely multicellular are: red algae brown algae green algae

Red Algae –What are the distinguishing features of red algae?

Brown Algae –What are the distinguishing features of brown algae?

Brown Algae Brown Alga Structure Blades Bladder Stipe Holdfast

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

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 Emerging amoebas Fruiting body Aggregated amoebas 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 Mature sporangium Young sporangium Mature plasmodium Feeding plasmodium Zygote Fertilization

Water Molds –What are the defining characteristics of the water molds?

Water Molds FERTILIZATION MEIOSIS SEXUAL REPRODUCTION ASEXUAL REPRODUCTION