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, whip-like 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?