General Biology of the Protists Origin of Eukaryotic Cell fileÐ Foraminiferans (phylum...
Transcript of General Biology of the Protists Origin of Eukaryotic Cell fileÐ Foraminiferans (phylum...
Mader: Biology 8th Ed.
The Protists
Chapter 22
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Outline
• General Biology
• Evolution
• Diversity
– Green Algae
– Red Algae
– Brown Algae
– Diatoms
– Dinoflagellates
• Diversity
– Euglenoids
– Zooflagellates
– Pseudopods
– Ciliates
– Sporozoans
– Slime Molds
– Water Molds
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General Biology of the Protists
• Protists are classified in the domain Eukarya and the kingdom Protista.
– Most are unicellular, but have achieved a high level of complexity.
– Asexual reproduction is common, but sexual reproduction can occur when the environment becomes stressful.
!Spores
!Cysts
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Origin of Eukaryotic Cell
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Evolution of Protists
• Complexity and diversity of protists makes them difficult to classify.
– Cannot be classified as plants, animals, or fungi.
– Has been suggested protists could be split into as many as a dozen kingdoms.
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Diversity of Protists
• Green Algae
– Green algae (phylum Chlorophyta).
!Chlamydomonas
"Unicellular
"Usually reproduces asexually
# Forms spores and zoospores when growth conditions are unfavorable.
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Green Algae
– Spirogyra
!Unbranched, filamentous alga found in masses on the surfaces of standing water.
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Green Algae
– Multicellular
!Ulva
!Stoneworts
!Chara
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Green Algae
– Colonial
!Volvox
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Flagellated Protists
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Red Algae
• Red Algae (phylum Rhodophyta)
– Multicellular, and live mostly in warmer seawater.
!Usually much smaller and more delicate than brown algae.
!Economic Importance
"Agar
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Brown Algae
• Brown Algae (phylum Phaeophyta)
– Have chlorophylls a and c in their chloroplasts and a carotenoid pigment.
– Often observed on rocky coasts in north temperate zone.
!Seaweeds
!Kelp
!Fucus
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Brown Algae
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The Diatoms
• Diatoms (phylum Bacillariophyta) are the most numerous unicellular algae in the oceans.
– Significant portion of phytoplankton.
– Structure composed of two valves, with the larger valve acting as a lid.
– Cell wall has outer layer of silica.
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The Dinoflagellates
• Most dinoflagellates (phylum Pyrrophyta) are unicellular.
– Usually bounded by protective cellulose plates impregnated with silicates.
!Typically contain two flagella.
!Chloroplasts vary in color.
!Usually reproduce asexually.
!Some genera may cause red tide.
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Diatoms and Dinoflagellates
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The Euglenoids
• Euglenoids (phylum Euglenophyta) are small freshwater unicellular organisms.
– Difficult to classify.
– Have two flagella and an eyespot (shades a photoreceptor).
– Bound by flexible pellicle.
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Euglena
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The Zooflagellates
• Zooflagellates (phylum Zoomastigophora) are colorless heterotrophs.
– Most are symbiotic and many are parasitic.
– Well known for causing various diseases in humans.
!African sleeping sickness
!Giardia lamblia
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Zooflagellates
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Protists with Pseudopods
• Pseudopods form when cytoplasm streams forward in a particular direction.
– Amoeboids (phylum Rhizopoda) are protists that move and ingest their food with pseudopods.
!Phagocytize food.
– Foraminiferans (phylum Foraminifera) and radiolarians (phlyum Actinopoda) both have a skeleton (test).
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Protists with Pseudopods
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Amoeboid Protists
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The Ciliates
• Ciliates (phylum Ciliophora) are most complex of the protozoans.
– Hundreds of cilia beat in coordinated rhythm.
– Most are holozoic.
– Divide by transverse binary fission during asexual reproduction.
– High level of diversity.
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Ciliates
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Ciliated Protists
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The Sporozoans
• Sporozoans (phylum Apicomplexa) are nonmotile parasites.
– Most widespread human parasite is Plasmodium vivax, the cause of one form of malaria.
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Plasmodium vivax Life Cycle
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Slime Molds
• Plasmodial Slime Molds
– (phylum Myxomycota) usually exist as a plasmodium.
!Diploid, multinucleated, cytoplasmic mass enveloped by a slime sheath.
"Sporangium produces spores.
• Cellular Slime Mold
– (phylum Acrasiomycota) exists as individual amoeboid cells.
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Plasmodial Slime Molds
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Water Molds
• Water molds (phylum Oomycota) usually live in the water and form furry growths when they parasitize fish and decompose remains.
– Have filamentous body with cell walls largely composed of cellulose.
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Review
• General Biology
• Evolution
• Diversity
– Green Algae
– Red Algae
– Brown Algae
– Diatoms
– Dinoflagellates
• Diversity
– Euglenoids
– Zooflagellates
– Pseudopods
– Ciliates
– Sporozoans
– Slime Molds
– Water Molds
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