Alveolata: Apicomplexa; Plasmodium sp. Infected mosquito bites human; sporozoites migrate through bloodstream to liver of human Sporozoites undergo schizogony in liver cell; merozoites are produced Merozoites released into bloodsteam from liver may infect new red blood cells Merozoites are released when red blood cell ruptures; some merozoites infect new red blood cells, and some develop into male and female gametocytes 1 2 3 4 6 Asexual reproduction Intermediate host Merozoite develops into ring stage in red blood cell Ring stage Merozoites Another mosquito bites infected humnan and ingests gametocytes 7 5 Ring stage grows and divides, producing merozoites Definitive host In mosquito’s digestive tract, gametocytes unite to form zygote 8 Male gametocyte Female gametocyte Zygote Sexual reproduction Resulting sporozoites migrate to salivary glands of mosquito 9 Sporozoites in salivary gland
Structure and Function in the Ciliate Paramecium caudatum
50 µm Thousands of cilia cover the surface of Paramecium. The undigested contents of food vacuoles are released when the vacuoles fuse with a specialized region of the plasma membrane that functions as an anal pore. Paramecium, like other freshwater protists, constantly takes in water by osmosis from the hypotonic environment. Bladderlike contractile vacuoles accumulate excess water from radial canals and periodically expel it through the plasma membrane. Food vacuoles combine with lysosomes. As the food is digested, the vacuoles follow a looping path through the cell. Paramecium feeds mainly on bacteria. Rows of cilia along a funnel-shaped oral groove move food into the cell mouth, where the food is engulfed into food vacuoles by phagocytosis. Oral groove Cell mouth Micronucleus Macronucleus FEEDING, WASTE REMOVAL, AND WATER BALANCE Contractile Vacuole Alveolata: Ciliates
CONJUGATION AND REPRODUCTION 8 7 2 MICRONUCLEAR FUSION Diploid micronucleus Diploid micronucleus Haploid micronucleus MEIOSIS Compatible mates Key Conjugation Reproduction Macronucleus Two cells of compatible mating strains align side by side and partially fuse. 1 Meiosis of micronuclei produces four haploid micronuclei in each cell. 2 3 Three micronuclei in each cell disintegrate. The remaining micro- nucleus in each cell divides by mitosis. The cells swap one micronucleus. 4 The cells separate. 5 Micronuclei fuse, forming a diploid micronucleus. 6 Three rounds of mitosis without cytokinesis produce eight micronuclei. 7 The original macro- nucleus disintegrates. Four micronuclei become macronuclei, while the other four remain micronuclei. 8 Two rounds of cytokinesis partition one macronucleus and one micronucleus into each of four daughter cells. 9 Alveolata: Ciliates
Brown algae (a) The seaweed is grown on nets in shallow coastal waters. (b) A worker spreads the harvested sea- weed on bamboo screens to dry. (c) Paper-thin, glossy sheets of nori make a mineral-rich wrap for rice, seafood, and vegetables in sushi.