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Protists • The kingdom protista is a diverse group that may include more than 200,000 species. • A protist is any organism that is not a plant an animal, a fungus, or a prokaryote. • Protists were the first eukaryotes on Earth 1.5 billion years ago. • Endosymbiosis? What's that? • Protists are so diverse that many biologists suggest that they should be broken up into several kingdoms. • This idea is supported by recent studies of protist DNA indicating that different groups of protists evolved independently from archaebacteria. Animal-like protists: Protozoans (zooflagellates, Sarcodines, Cilliates, Sporozoans) • ZOOFLAGELLATES • Absorb food through cell membrane. Many live in lakes and streams. Others in the bodies of other organisms. Most reproduce asexually by mitosis. • Few have a sexual life cycle. Motility is possible due to a flagellum. Some are parasitic: Trypanosoma ~ African sleeping sickness. • SARCODINES • Motility possible via cytoplasmic projections called pseudopods. These structures are also used for feeding. The most common is the amoeba. • SARCODINES • Foraminiferans ~ calcium carbonate (CaCO3) / Heliozoans ~ silica (SiO2) Heliozoan • CILIATES • Ciliates are found in both fresh and salt water. Most are free living. Motility via cilia, short hair like projections. Most common ciliate: Paramecium ~ the image on the homepage of the website. Animal-like protists: Protozoans (zooflagellates, Sarcodines, Cilliates, Sporozoans) • SPOROZOANS • This group of protist is parasitic. Reproduce via sporozoites. Most common: Plasmodium which causes malaria. • Many play an important role in the world. Some live symbiotically with other organisms, others recycle nutrients by breaking down organic matter. • Some serve as food for other small organisms. Some are very beneficial to other organisms like Trichonympha, a zooflagellate that lives in the digestive system of termites. These protist break down the cellulose in wood! Not the termite... Plant-like Protists: Unicellular algae • EUGLENOPHYTES Plant like protists that have two flagella but no cell wall. Photosynthetic and heterotrophic / Eyespot (red) • CHRYSOPHYTES (golden plant) Yellow-green algae and the golden-brown algae. • DIATOMS Diatoms produce thin, delicate cell walls rich in silicon (Si) - the main component of glass. • DINOFLAGELLATES Half are photosynthetic and half heterotrophic. Many are luminescent, and when agitated by sudden movement in the water, give-off light. Plant-like Protists: Unicellular algae • Phytoplankton is the group of small, photosynthetic organisms found near the surface of the ocean. About half of the photosynthesis that occurs on Earth is carried out by phytoplankton. Primary producers too... • Algal Blooms ~ absorb organic material directly and use it for food. Grow rapidly in waters where sewage is discharged. Play important role in recycling these wastes. When waste is excessive, they grow to great masses (blooms). These blooms deplete the water of oxygen when they consume all the nutrients and die. This disrupts the equilibrium of the ecosystem causes fish and invertebrate die-offs. (red tide) • Can accumulate in certain shell-fish which in turn are eaten by humans causing illness, even death. Plantlike Protists: Red, Brown, and Green Algae • Beach at low tide? • RED ALGAE (Rhodophyta ~ red plants) Able to live at great depths due to their ability to harvest light energy. (Chrorophyll a) • BROWN ALGAE (Phaeophyta ~ dusky plants) The largest of the algae. Chlorophyll a, c and brown pigments. Giant kelp - 60 meters in length. • GREEN ALGAE (Chlorophyta ~ green plants) Share many characteristics with plants including photosynthetic pigments and cell wall composition. Closely related to mosses. Marine & freshwater. Unicellular - Colonial multicellular Human uses: • • • • • • • • • • 50% of O2 production Sushi Plastics Waxes Transistors Deodorants Paints Lubricants Artificial wood Agar The End Vocabulary / Home learning assignment 1. Protist 2. Pseudopoda 3. Amoeboid movement 4. Food vacuole 5. Cilium 6. Macronucleus 7. Micronucleus 8. Gullet 9. Contractile vacuole 10.Conjugation 11.Eyespot 12.Phytoplankton 13.Spore 1st period: ~ read pages 350 – 368 and observe all pictures!!! _____________________ 2nd thru 6th periods: ~ read pages 356 – 368 and observe all pictures!!!
