Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr Chapter 20 The Protists (Sections )

20.1 Harmful Algal Blooms Aquatic protists include single-celled and multicellular autotrophs and heterotrophs An algal bloom is a population explosion of an aquatic protist, or of another aquatic microorganism Toxins released during some algal blooms can harm wildlife and endanger human health

Key Terms protist Eukaryote that is not a fungus, animal, or plant algal bloom Population explosion of tiny aquatic producers toxin Chemical that is made by one organism and harms another

Karenia brevis This dinoflagellate produces brevetoxin, which interferes with nerve cells of people and animals who inhale or ingest it

20.2 A Collection of Lineages Protists are a collection of mostly single-celled eukaryotes Many have chloroplasts that evolved from cyanobacteria or another protist The dominant stage of the life cycle may be haploid or diploid Protists are not a natural group, but a collection of lineages, some only distantly related to one another

Protist Diversity

Fig. 20.2a, p. 312 Protist Diversity

Fig. 20.2b, p. 312 Protist Diversity

Fig. 20.2c, p. 312 Protist Diversity

Fig. 20.2d, p. 312 Protist Diversity

Fig. 20.2e, p. 312 Protist Diversity

Protist Groups Protists are not a single lineage One proposed eukaryotic family tree with protist groups indicated by tan boxes

Fig. 20.2f, p. 312 ancestral cells Amoebozoans Stramenopiles Flagellated Protozoans Alveolates Green Algae fungi slime molds amoebas land plants charophyte algae chlorophyte algae red algae brown algae diatoms water molds apicomplexans dinoflagellates ciliates foraminiferans radiolarians euglenoids trypanosomes parabasalids diplomonads animals choanoflagellates F Protist Groups

Key Concepts A Collection of Lineages Protists include many lineages of eukaryotic organisms, some autotrophs and others heterotrophs Protists are not a clade; some groups are more closely related to plants, or to fungi and animals, than to other protists

20.3 Flagellated Protozoans Flagellated protozoans are single cells with no cell wall – a protein covering (pellicle) helps maintain the cell’s shape flagellated protozoan Protist belonging to an entirely or mostly heterotrophic lineage with no cell wall and one or more flagella pellicle Layer of proteins that gives shape to many unwalled, single-celled protists

Diplomonads and Parabasalids Diplomonads and parabasalids have multiple flagella and are adapted to oxygen-poor habitats Instead of mitochondria, they have organelles that produce ATP by an anaerobic pathway Both groups include species that infect humans

A Diplomonad Diplomonads have two more or less identical nuclei Giardia lamblia causes giardiasis, a waterborne intestinal disease

A Parabasalid Trichomonas vaginalis causes a sexually transmitted disease

Trypanosomes trypanosome Parasitic flagellate with a single mitochondrion and a membrane-encased flagellum Insects transmit trypanosomes, such as Trypanosoma brucei, which causes African sleeping sickness

Euglenoids euglenoid Flagellated protozoan with multiple mitochondria Some have chloroplasts that evolved by secondary endosymbiosis from a green alga Typically live in fresh water Have a contractile vacuole contractile vacuole In freshwater protists, an organelle that collects and expels excess water

Body Plan of Euglena

Fig. 20.4, p. 313 nucleus long flagellum contractile vacuole pellicleGolgi bodymitochondrion ER eyespot chloroplast Body Plan of Euglena

ANIMATION: Body plan of Euglena To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

20.4 Mineral-Shelled Protozoans Foraminiferans and radiolarians are single-celled marine protists with sieve-like shells They capture food with microtubule-reinforced cytoplasmic extensions that protrude through the shell’s openings Both are marine heterotrophs and may be part of plankton plankton Community of tiny drifting or swimming organisms

Foraminiferans and Radiolarians foraminiferan Heterotrophic single-celled protist with a chalky calcium carbonate shell and long cytoplasmic extensions Deposits of their remains are mined for chalk and limestone radiolarian Heterotrophic single-celled protist with a glassy silica shell and long cytoplasmic extensions that stick out through the porous shell and capture prey

Foraminiferans and Radiolarians

Fig. 20.5a, p. 314 Foraminiferans and Radiolarians

Fig. 20.5b, p. 314 Foraminiferans and Radiolarians

Fig. 20.5c, p. 314 Foraminiferans and Radiolarians