Ch. 7 Protists Section 3: Protists • What is a Protist? – Protists: are eukaryotes that cannot be classified by animals, plants, or fungi – All protists live in moist surroundings – Protists are diverse because most are unicellular, but some are multicellular, some are heterotroph, and autotrophs – Some protists don’t move, while others zoom around their moist surroundings Section 3: Protists • Animal-Like Protists – Like animals, animal-like protists are heterotrophs, and most are able to move from place to place to obtain food – Protozoans: animal-like protists, unicellular Section 3: Protists • Animal-Like Protists – Protozoans with Pseudopods • Pseudopods: “false foot” • Pseudopods form when cytoplasm flows toward one location and the rest of the organism follows • An Amoeba is an example of a protozoan that live in fresh water • Small particles, like those of water, pass easily through the cell membrane into the cytoplasm • If excess water were to build up inside the cell, the amoeba would burst • Contractile vacuole: a structure that collects the extra water and then expels it from the cell Section 3: Protists • Animal-Like Protists – Protozoans with Cilia • The second group of animal-like protists are the ciliates • Cilia: which are hair-like projections from cells that move with a wavelike motion • Ciliates use their cilia to move and obtain food • The cells of ciliates, like the paramecium has two contractile vacuoles that expel water from the cell. • Has more than one nucleus • Produce asexually by binary fission • What are cilia? Section 3: Protists • Animal-Like Protists – Protozoans with Flagella • Third group is flagella which are protists that use long, whiplike flagella to move • Some live inside the body of other organisms – Example: one type of flagella live inside the intestines of termites • Symbiosis: interaction between two species; a close relationship in which at least one of the species benefits • Mutualism: when both partners benefit from living together – Example: Giardia is a parasite that lives in humans; comes from wild animals such as beavers Section 3: Protists • Animal-Like Protists – Protozoans that are Parasites • Fourth type is characterized by the way they live then by the way they move • They are parasites that feed on the cells of body fluids of their hosts • Many have more than one host – Example: Plasmodium: protozoan that causes malaria (disease of the blood) – What is symbiosis? Section 3: Protists • Plantlike Protists – Algae: are autotrophs using the suns energy to make their own food – Algae play a significant role in the environment • Example: algae that live near the surface of ponds, lakes, and oceans are an important food source for other organisms in the water – Algae very in size • Unicellular • Multicellular • Live in colonies – Algae very in color • They consists of many pigments Section 3: Protists • Plantlike Protists – Diatoms • Unicellular protists with beautiful glasslike cell walls • Some float on the surface of water, some attach to rocks in shallow water • Food source for heterotrophs • Move by oozing chemicals out of slits in their cell walls • When they die, their cell walls collect on the bottom of lakes or oceans • Diatomaceous: layer forming coarse substance Section 3: Protists • Plantlike Protists – Dinoflagellates • Unicellular algae surrounded by stiff plates that look like a suit of armor • Exists in different colors such as green or orange • Glow in the dark • Have 2 flagella help in grooves between their plates • When the flagella beat, the dinoflagellates twirl like toy tops as they move through the water Section 3: Protists • Plantlike Protists – Euglenoids • Green, unicellular algae that are found mostly in fresh water • Can be either autotrophs or heterotrophs • Whiplike flagellum to help it move Section 3: Protists • Plantlike Protists – Red Algae • Multicellular seaweed • Grow more than 260m below the ocean’s surface • People use red algae in many ways: – Ice cream – Hair conditioner – Eat it fresh, dried, or toasted (Asian cultures) Section 3: Protists • Plantlike Protists – Green Algae • Very diverse, unicellular, but some form colonies and are multicellular • Live in fresh, salt water, or on land found on rocks, crevices on tree bark, or in moist soils • Green algae and plants that live on land have similar characteristics – Same chlorophyll Section: Protists • Plantlike Protists – Brown Algae • Example: seaweed, Giant kelp • Different pigments besides brown are: green, yellow, and orange • Plantlike structures: holdfasts, stalks (leaf-like structures), and gas-filled sacs called bladders • Live in cool, rock waters off the coast of the Atlantic Ocean • People eat brown algae and its used as a thickener in pudding • What color pigments can brown algae contain? Section 3: Protists • Funguslike Protists – Spore: is a tiny cell that is able to grow into a new organism – Like fungi, funguslike protists are hetertrophs, have cell walls, and use spores to reproduce – Slime Molds • Brilliantly colored • Live on forest floors • Ooze on the surfaces of decaying materials, feeding on bacteria and other microorganisms • Life cycle: tiny amoeba-like cells, use pseudopods to feed and creep around, cells grow bigger and form a jellylike mass • When the environment conditions become harsh, the mass releases spores Section 3: Protists • Funguslike Protists – Water Molds and Downy Mildews • Live in water or moist places • Grow as tiny threads and look like fuzz • Attack many food crops such as: potatoes, corn, and grapes • In what environments are water molds found?