eukaryotes that are not plants, animals, or fungi have traditionally been called protists. the term...
TRANSCRIPT
![Page 1: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/1.jpg)
![Page 2: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/2.jpg)
• Eukaryotes that are not plants, animals, or fungi have traditionally been called protists.
• The term does not describe a formal taxonomic group, but is a convenience term.
• Eukaryotes are monophyletic.• They are thought to be more closely related to
Archaea than to Bacteria.• But mitochondria and chloroplasts are clearly
derived from bacterial lineages.
![Page 3: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/3.jpg)
Events in the origin of the eukaryotic cell:• Cell wall was lost• Cytoskeleton formed• Nuclear envelope developed• Digestive vacuoles appeared• Mitochondria formed by endosymbiosis
![Page 4: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/4.jpg)
•Eukaryotes evolved as “symbiotic consortiums” ofprokaryotic cells•Have observed similar behavior in amoebas containing symbiotic bacteria•DNA evidence: mitochondria, cholorplast, centriole found to have own DNA- different from eukaryotic cell- more like endosymbiotic bacteria
![Page 5: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/5.jpg)
• Development of chloroplasts occurred in a series of endosymbioses.
• Primary endosymbiosis: a cyanobacterium was engulfed. Chloroplast has two membranes. Remnants of peptidoglycan cell wall can be found in glaucophytes.
• Primary endosymbiosis also gave rise to chloroplasts of red algae, green algae, and land plants.
![Page 6: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/6.jpg)
• Secondary endosymbiosis: a eukaryote engulfed a green alga cell which became a chloroplast.
• Chloroplast has three membranes.• Tertiary endosymbiosis: a dinoflagellate lost its
chloroplast and took up another protist that had acquired its chloroplast through secondary endosymbiosis.
![Page 7: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/7.jpg)
There are five major clades of protistan eukaryotes.• There is enormous diversity within these groups.• Most are unicellular and microscopic; but some are
multicellular and some are quite large (e.g., giant kelp).
• Protists were traditionally classified on the basis of life histories and reproductive features.
• Today, electron microscopy and gene sequencing reveal more evolutionary patterns.
• Lateral gene transfer may be a complicating factor.
![Page 8: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/8.jpg)
![Page 9: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/9.jpg)
Alveolates• Sacs called alveoli lie just beneath plasma
membrane. • All unicellular, most are photosynthetic.
• Dinoflagellates• Apicomplexans• Ciliates
Dinoflagellates: mostly marine; photosynthetic; important primary producers in the oceans.
• Some species cause red tides.
• Some are endosymbionts with invertebrates (e.g., corals).
![Page 10: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/10.jpg)
Apicomplexans: obligate parasites• Apical complex—organelles at the tip of the cell;
help it invade host tissue.• Elaborate life cycles featuring asexual and sexual
reproduction and life stages in different hosts.• Plasmodium is the causative agent of malaria.
![Page 11: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/11.jpg)
Ciliates: numerous hairlike cilia (identical to eukaryotic flagella).
• Heterotrophic; some have photosynthetic endosymbionts.
• Complex body form.
![Page 12: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/12.jpg)
• The ciliate Paramecium is covered by a flexible pellicle with trichocysts—defensive organelles that can explode as sharp darts.
• Cilia provide precise locomotion.• Lives in fresh water: contractile vacuoles excrete
excess water taken in by osmosis.• Also has digestive vacuoles.
![Page 13: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/13.jpg)
• Excavates
• Diplomonads
• Parabasalids
• Heteroloboseans
• Euglenids
• Kinetoplastids
• Diplomonads and parabasalids: unicellular and lack mitochondria (a derived condition).
• Giardia lamblia causes the intestinal disease giardiasis.
![Page 14: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/14.jpg)
Heteroloboseans: amoeboid body form• Naegleria has two stages, one with amoeboid cells
and the other with flagellated cells.• Some species can enter the human body and cause
a fatal disease of the nervous system.
![Page 15: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/15.jpg)
Euglenids and kinetoplastids: have flagella; mitochondria with disc-shaped cristae.
• Some euglenids are always heterotrophic; some are photosynthetic but can loose their pigments and feed on organic matter.
![Page 16: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/16.jpg)
Stramenopiles• Rows of tubular hairs on the longer of their two
flagella• Some lack flagella but are descended from
ancestors that possessed them.
• Diatoms
• Brown algae
• Oomycetes
![Page 17: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/17.jpg)
Diatoms: unicellular; some species associate in filaments
• Lack flagella except in male gametes.• Deposit silicon dioxide in two-piece cell walls;
intricate patterns are unique to each species.• Reproduce both sexually and asexually.• Abundant in oceans and fresh waters and are major
photosynthetic producers.
![Page 18: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/18.jpg)
Brown algae: brown color from the carotenoid fucoxanthin.
• Multicellular, marine.• Attached forms develop holdfasts with alginic acid
to glue them to rocks. Alginic acid is used by humans as an emulsifier in ice cream, cosmetics, and other products.
• Giant kelps may be up to 60 meters long.
![Page 19: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/19.jpg)
Oomycetes: water molds, downy mildews• Once classed as fungi• All are absorptive heterotrophs—secrete enzymes
that digest large food molecules into smaller molecules that they can absorb.
• Water molds—all aquatic and saprobic (feed on dead organic matter).
![Page 20: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/20.jpg)
Rhizaria• Unicellular and mostly aquatic; have long, thin
pseudopods.• Make up a large component of ocean sediments.
• Cercozoans
• Foraminiferans
• RadiolariansCercozoans: soil and aquatic organisms• One group has chloroplasts derived from a green
alga by secondary endosymbiosis—and that chloroplast contains a trace of the alga’s nucleus.
![Page 21: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/21.jpg)
• Foraminiferans: external shells of calcium carbonate
• Threadlike, branched pseudopods extend through microscopic holes in the shell and form a sticky net, used to catch smaller plankton.
• Accumulations of shells have produced much of the world’s limestone.
![Page 22: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/22.jpg)
Radiolarians: radial symmetry; thin, stiff pseudopods reinforced by microtubules.
• Pseudopods increase surface area of the cell, and help it stay afloat.
• Secrete glassy endoskeletons
![Page 23: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/23.jpg)
Amoebozoans• Amoeboid body form; lobe-shaped pseudopods
• Loboseans
• Plasmodial slime molds
• Cellular slime molds
![Page 24: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/24.jpg)
Loboseans: feed by phagocytosis, engulfing smaller organisms and particles with pseudopods.
• Many are adapted to living on the bottoms of lakes and ponds.
• Testate amoebas live in shells made from sand grains or secreted by the organism.
![Page 25: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/25.jpg)
Plasmodial slime molds: • Vegetative state—plasmodium—a mass of
cytoplasm with no cell walls and many diploid nuclei (a coenocyte).
• Moves by cytoplasmic streaming and engulfs food particles by endocytosis.
![Page 26: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/26.jpg)
![Page 27: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/27.jpg)
Asexual reproduction among the protists:• Binary fission—equal splitting by mitosis
followed by cytokinesis.• Multiple fission—splitting of one cell into
more than two cells.• Budding—outgrowth of a new cell from the
surface of an old one.• Sporulation—formation of specialized cells
that can develop into new individuals.
![Page 28: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/28.jpg)
Reproduction in Paramecium:• Two types of nuclei—one macronucleus and one to
several micronuclei.• Asexual reproduction—all nuclei are copied before
the cell divides. • Conjugation—two individuals fuse and exchange
genetic material; a sexual process, but not reproductive.
![Page 29: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/29.jpg)
Some protists have alternation of generations.
• A multicellular, diploid, spore-producing organism gives rise to a multicellular, haploid, gamete-producing organism.
• When two haploid gametes fuse, a diploid organism is produced.
• The haploid organism, the diploid organism, or both may also reproduce asexually.
![Page 30: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/30.jpg)
In the diploid organism, specialized cells called sporocytes divide meiotically to produce haploid spores.
• Spores develop into the haploid organism.• The haploid organism produces gametes by
mitosis and cytokinesis.• Gametes fuse to produce the diploid
organism.
![Page 31: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/31.jpg)
Phytoplankton are important primary producers.• The diatoms perform about 1/5 of all carbon
fixation on Earth—about the same amount as the rainforests.
Some microbial eukaryotes are pathogens.• Plasmodium is a parasite in human red blood cells
and causes malaria, one of the world’s most serious diseases.
• Plasmodium has a complex life cycle that includes mosquitoes as an alternate host.
• Plasmodium is an extracellular parasite in the mosquito and an intracellular parasite in the human host.
![Page 32: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/32.jpg)
Many microbial eukaryotes live as endosymbionts.• Some photosynthetic dinoflagellates live as
endosymbionts in corals. If the dinoflagellates die or are expelled, the coral is said to be bleached.
• If the corals don’t acquire new endosymbionts, they usually die or are damaged due to reduced food supply.
![Page 33: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/33.jpg)
• Diatoms store energy as oil. Over millions of years, diatoms have died and sunk to the ocean floor, ultimately becoming petroleum and natural gas.
• Diatomaceous earth is sedimentary rock composed mostly of the silica cell walls of diatoms; used for insulation, filtration, metal polishing, and to kill insects (it clogs their breathing tubes).
• Foraminiferan shells make up extensive limestone deposits, and some sandy beaches.
• The shells are preserved as fossils in marine sediments and are used to estimate past environmental parameters such as sea temperature.
• Fossil shells in rocks are used in stratigraphy and dating of the rocks.
![Page 34: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/34.jpg)
Dinoflagellates are important components of marine ecosystems.
• Corals and other species depend on symbiotic dinoflagellates for photosynthesis.
• They are important primary producers, providing food for many species and much of the atmospheric oxygen.
• Some species produce beautiful bioluminescence in the oceans.
![Page 35: Eukaryotes that are not plants, animals, or fungi have traditionally been called protists. The term does not describe a formal taxonomic group, but is](https://reader036.vdocuments.mx/reader036/viewer/2022081519/56649d065503460f949d94ba/html5/thumbnails/35.jpg)