3Key Facts on Protists Eukaryotic Hetereotrophic or autotrophic Reproduce sexually or asexuallyLive in aquatic or other moist environments
4Importance of Protists Protists play key roles in aquatic ecosystems.Protists that perform photosynthesis along with some other prokaryotes, are the major producers in the world’s oceansNon-photosynthetic protists are consumers that dominate the lowest levels of most aquatic food pyramids
5Importance of Protists con’t Many protists are parasites – they live in, or on, other organismsMost parasites do not harm their host organism, but some cause serious disease (ex: malaria, sleeping sickness, ameobic dysentry, beaver fever)
7Importance of Protists Human Uses of Protistssushi (nori is a multicellular protist Porphyra)Agar and carrageeenan (both are food additives)
8OriginProtists were the first eukaryotes – their cells have a nucleus and organelles bound by membranes.These internal membranes likely developed from the folded cell membrane of an ancestral prokaryotic cell.This folding would have increased the cell surface area, allowing the cell to better exchange materials with its environment. This ability is a necessary feature of large cells.
10Origins – Chloroplasts & Mitochondria Present-day mitochondria and chloroplasts each have two membranesTheir inner membranes are similar to those of their ancestral prokaryote, while their outer membranes match the cell membranes of the eukaryotes
12Origins – Chloroplasts & Mitochondria Present-day mitochondria and chloroplasts have their own internal chromosomes (DNA)These chromosomes are very similar to prokaryote chromosomes and contain genetic information used by the organellesMitochondria and chloroplasts reproduce independently within eukaryotic cells by binary fission, just as prokaryotes do
13Origins – Chloroplasts & Mitochondria Because of all of those features, we believe that mitochondria and chloroplasts are thought to have originated by endosymbiosis.ENDOSYMBIOSIS: a relationship in which a single-celled organism lives within the cells of another organism
14Origins – Chloroplasts & Mitochondria....conclusion: Mitochondria and chloroplasts were once prokaryotic organisms. These cells were engulfed by early anaerobic eukaryotic cells and incorporated into them.We believe that mitochondria were once aerobic prokaryotes that benefitted from a rich food supply, while the eukaryotes benefited from the excess energy released by the areobic prokaryote
16Typical ProtistsThere are no typical protists! Many protists are parasites that can may or may not harm their host. Malaria is a disease that is caused by a harmful protist called Plasmodium that is transmitted using a mosquito as a vector.Protists can be unicellular or multicellular. They vary in their cell features, ways of moving, ways of getting nutrients and methods of reproducing.
22Ecosystems and Protists Protists play key roles in ecosystems as producers or consumers.For example, the large green, red, and brown algae called seaweeds have gas-filled bladders that help them float toward the light .This allows them to produce energy through photosynthesis.Photosynthetic protists are the primary producers in aquatic food webs.The large kelps, belonging to the brown algae group, can grow up to a half metre a day and reach a length of 80 m!
23Climate Change and Protists Climate change is affecting many protists, including algae. In aquatic ecosystems the temperatures of oceans and lakes are rising.The water is also becoming more acidic, which may interfere with some protists’ ability to produce their outer protective shells.Without their protective shells, they may not survive.- The loss of these protists may severely damage food webs that rely on the photosynthetic products they create.
24Life Cycles Protists reproduce sexually and asexually Single Cell ProtistsAsexually – Binary FissionSexually – ConjugationMulti-cellular ProtistsSexually – Sex Cells (ie male spermand female egg)
27Comprehension Homework: 2. Some protists are closely related to animals, plants or fungi than they are to each other. What does this suggest about the classification criteria used for members in this kingdom.
28Homework Homework: (Research) African sleeping sickness is a serious parasitic disease caused by the protist, Trypanosoma brucei. Use the Internet to find out more about this disease. Where in the world is it most prevalent? How is it spread? What are the symptoms? Can the disease be effectively treated?Go to the WHO website (or other sites) to learn more about malaria. How is it spread? How prevalent is it in the world? How can it be prevented? How is malaria connected to sickle-cell anemia?