chapter 20 the protists (sections 20.1 - 20.4)
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Chapter 20 The Protists (Sections 20.1 - 20.4). 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 - PowerPoint PPT PresentationTRANSCRIPT
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Albia Dugger • Miami Dade College
Cecie StarrChristine EversLisa Starr
www.cengage.com/biology/starr
Chapter 20The Protists(Sections 20.1 - 20.4)
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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
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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
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Karenia brevis
• This dinoflagellate produces brevetoxin, which interferes with nerve cells of people and animals who inhale or ingest it
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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
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Protist Diversity
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Fig. 20.2a, p. 312
Protist Diversity
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Fig. 20.2b, p. 312
Protist Diversity
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Fig. 20.2c, p. 312
Protist Diversity
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Fig. 20.2d, p. 312
Protist Diversity
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Fig. 20.2e, p. 312
Protist Diversity
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Protist Groups
• Protists are not a single lineage
• One proposed eukaryotic family tree with protist groups indicated by tan boxes
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Fig. 20.2f, p. 312
ancestral cells
Amoebozoans
Stramenopiles
Flagellated Protozoans
Alveolates
Green Algae
fungi
slime moldsamoebas
land plantscharophyte algaechlorophyte algae
red algae
brown algaediatomswater molds
apicomplexans
dinoflagellatesciliates
foraminiferansradiolarians
euglenoidstrypanosomesparabasalidsdiplomonads
animalschoanoflagellates
F
Protist Groups
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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
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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
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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
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A Diplomonad
• Diplomonads have two more or less identical nuclei
• Giardia lamblia causes giardiasis, a waterborne intestinal disease
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A Parabasalid
• Trichomonas vaginalis causes a sexually transmitted disease
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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
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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
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Body Plan of Euglena
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Fig. 20.4, p. 313
nucleus
long flagellum
contractile vacuole
pellicle Golgi body mitochondrion
ER
eyespot
chloroplast
Body Plan of Euglena
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ANIMATION: Body plan of Euglena
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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
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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
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Foraminiferans and Radiolarians
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Fig. 20.5a, p. 314
Foraminiferans and Radiolarians
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Fig. 20.5b, p. 314
Foraminiferans and Radiolarians
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Fig. 20.5c, p. 314
Foraminiferans and Radiolarians