Microsoft PowerPoint - 28- protists revised.pdf - NSD Main

Apicomplexans• Apicomplexans– Are parasites of animals and some causeserious human diseases– Are so named because one end, the apex,contains a complex of organelles specializedfor penetrating host cells and tissues– Have a nonphotosynthetic plastid, theapicoplast• Most apicomplexans have intricate life cycles– With both sexual and asexual stages that often requiretwo or more different host species for completion1 An infected Anopheles2 The sporozoites enter the person’smosquito bites a person,liver cells. After several days, the sporozoitesinjecting Plasmodiumundergo multiple divisions and becomesporozoites in its saliva.merozoites, which use their apical complexto penetrate red blood cells (see TEM below).Inside mosquitoInside humanMerozoiteSporozoites(n)Liver7 An oocyst developsfrom the zygote in the wallLiver cellof the mosquito’s gut. Theoocyst releases thousandsof sporozoites, whichOocystApexmigrate to the mosquito’ssalivary gland. MEIOSISMerozoiteRed blood 0.5 µm(n)cellZygoteRed blood(2n)cells3 The merozoites divide asexually inside thered blood cells. At intervals of 48 or 72 hours(depending on the species), large numbers ofmerozoites break out of the blood cells, causingperiodic chills and fever. Some of the merozoitesFERTILIZATIONinfect new red blood cells.KeyHaploid (n)Diploid (2n)GametesGametocytes(n)4 Some merozoitesform gametocytes.Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings6 Gametes form from gametocytes.Fertilization occurs in the mosquito’sFigure 28.11 digestive tract, and a zygote forms.The zygote is the only diploid stagein the life cycle.Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings5 Another Anopheles mosquitobites the infected person and picksup Plasmodium gametocytes alongwith blood.Ciliates• Ciliates, a large varied group of protists• The micronuclei– Are named for their use of cilia to move andfeed– Have large macronuclei and small micronuclei– Function during conjugation, a sexual processthat produces genetic variation• Conjugation is separate from reproduction– Which generally occurs by binary fissionCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings• Concept 28.5: Stramenopiles have “hairy” andsmooth flagella• The clade Stramenopila– Includes several groups of heterotrophs aswell as certain groups of algaeOomycetes (Water Molds and Their Relatives)• Oomycetes– Include water molds, white rusts, and downymildews– Were once considered fungi based onmorphological studiesCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings4