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Chapter 21 Protists Section 1: Characteristics of Protists Section 2: Protist Diversity Section 3: Protists and Health Section 1 Characteristics of Protists Objectives: •List the characteristics of protists. •List three environments where protists can be found. •Identify the unifying features of protists. •Distinguish asexual and sexual reproduction of Chlamydomonas. •Differentiate two ways multicellular protists reproduce sexually. Section 1 Characteristics of Protists Diversity •Characteristics The kingdom Protista contains the most diverse groups of eukaryotic organisms of any kingdom. Protists live in moist environments and can be either free-living or parasitic. •The First Eukaryotes Protists were the first eukaryotes to have evolved about 1.5 billion years ago. •What Unites Protists The kingdom Protista contains all eukaryotes that cannot be classified as animals, plants, or fungi. Section 1 Characteristics of Protists Reproduction •Sexual Reproduction in Unicellular Protists Some unicellular protists can reproduce sexually in times of stressful environmental conditions. •Sexual Reproduction in Multicellular Protists Two ways that sexual reproduction occurs in multicellular protists are alternation of generations and conjugation. Section 2 Protist Diversity Objectives: •Identify how amoebas and forams move. •Describe the structure of diatoms. •Contrast three kinds of algae. •Differentiate three different kinds of flagellates. •Summarize the general characteristics of a Paramecium. Section 2 Protist Diversity Ameboid Movement •Amoebas Amoebas move using cytoplasmic extensions called pseudopodia. •Foraminifera Forams have porous shells, called tests. Long, thin projections of cytoplasm extend through the pores in the tests to aid in swimming and catching prey. Section 2 Protist Diversity Algae •Characteristics Algae are strictly photosynthetic protists that can be multicellular or unicellular. Algae are classified based on the type of photosynthetic pigment they contain. •Green Algae Green algae are multicellular or unicellular and contain chlorophyll. •Red Algae Red algae are multicellular with red pigments and have a complex life cycle. •Brown Algae Brown algae are multicellular with brown pigments and contain the largest organisms on earth. Section 2 Protist Diversity Diatoms •Diatoms Diatoms are unicellular protists with glasslike double shells. Section 2 Protist Diversity Flagellates •Characteristics Flagellates move with the use of a flagella. •Dinoflagellates Dinoflagellates are associated with poisonous “red tides.” •Euglenoids Euglenas have chloroplasts and an eye spot. Section 2 Protist Diversity Flagellates continued •Kinetoplasts Some kinetoplasts live symbiotically in the guts of termites where they provide the enzymes that digest wood. •Ciliates Ciliates are the most complex and unusual of the protists that contain cilia for mobility and feeding. Section 2 Protist Diversity Protistan Molds •Characteristics Protistan molds resemble fungi, but they are considered protists. •Cellular Slime Molds Cellular slime molds normally live as individual cells and aggregate for sexual reproduction. •Plasmodial Slime Molds Plasmodial molds live as colonial organisms and form sexual reproductive structures that form and spread spores. •Other Molds Oomycetes are molds that live as saprophytes or parasites. Section 2 Protist Diversity Sporozoans Characteristics All sporozoans are parasitic and have complex life cycles. Section 3 Protists and Health Objectives: •Identify two ways that protists affect human health. •Name three human diseases, other than malaria, caused by protists. •Summarize how malaria is transmitted. •Evaluate the methods used to control malaria. Section 3 Protists and Health Protists and Humans •Beneficial Protists Protists positively affect human health through their participation in food webs, through commensal relationships with humans and their food sources, and by recycling vital resources. Section 3 Protists and Health Malaria •Disease and Protists Protists negatively affect human health by causing diseases in humans and their food sources. Protists cause diseases such as dysentery, giardiasis, toxoplasmosis, and malaria. •Malaria Life Cycle Protist, Plasmodium, has a complex life cycle that involves a mosquito, human blood, and liver cells. •Treating and Preventing Malaria Drugs and mosquito control can be used to control malaria.