Post on 24-Feb-2016
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Chapter 22Protists
ProtistsSimplest eukaryotic cellsEukaryotic characteristics
Nucleus and other complex organelles
Organelle—internal membrane-bound compartment that serves specialized functions. “Little organs”
More than one chromosomeProtozoansAlgaeFungiPlantsAnimals
ProtistsVery diverse!Some may resemble plants, fungi, or animals
Lack complexity of “higher” organismsProtozoa—“first animal”
ProtistsTaxonomy questionable & confusingTraditionally organized by motility
AmoeboidCilliateFlagellateSporozoans
Organize by evolutionary relationshipParabasalids & diplomonadsEuglenoids & kinetoplastidsRadiolarians & foraminiferansAlveolates & streamenophilesAmoebozoans
Protozoal MovementFlagella—long
outer structures for movementUsually only a
fewCilia—short
outer structures for movementUsually many“Hair-like”
Pseudopod“False foot”
Amoeboid ProtozoansAmoeba proteus
“Classic” amoebaPredatoryPseudopodsSee it move!
Entamoeba histolyticaFound in contaminated waterCauses diarrhea
50 million cases annually 100,000 deaths annually
Amoeboid ProtozoansForaminiferans
Form shells Mostly calcium carbonate
Pseudopods protrude through holes (foramen) in shells
Over long spans, form chalk & limestone
Amoeboid ProtozoansRadiolarians
Form shells Perforated Short silica rods
Numerous short, stiff pseudopods
Part of plankton
Ciliate ProtozoansMost free-living heterotrophsFeed on algae, bacteria, each
other1/3 symbionts or parasites
Ciliated ProtozoansParamecium
“Typical” ciliateCilia sweep water w/ food
into gulletMacronucleus &
micronucleus Micronucleus has full
genome but doesn’t transcribe
Ciliate Protozoans“Sexual” & asexual reproduction
(Fig 22.8) Physical contact, cytoplasmic fusion Micronucleus undergoes meiosis
One 2n micronucleus Four n micronuclei
3 of 4 mironuclei dissolve Remaining micronucleus undergoes
mitosis, making 2 micronuclei Cells exchange one micronucleus Cells separate Original macronucleus dissolves Micronuclei divide (making 4) Two micronuclei develop into
macronuclei Cell divides
Ciliate ProtozoansStentor
Filter feederOne of largest single-
celled organisms Several millimeters!
Cilia around mouth create current
See it in action!
Ciliate ProtozoansDidinium
Free-living predatorsTwo rings of ciliaMostly feed on
ParameciumToxin paralyzes prey’s
ciliaCan live in cysts for 10
yearsSee it hunting!Longer, but has great
close-up!
Flagellate ProtozoansKinetoplastids
Mitochondria almost as long as bodyTrypanosoma brucei
African sleeping sicknessTransmitted by tsetse flyEnters spinal fluid & brain
Flagellate ProtozoansEuglenoids
1/3 Heterotrophs2/3 PhotoautotrophsEye spot (stigma)
Detects lightEuglena
Sporozoan ProtozoansNo structures for movementAll are parasiticComplex life cyclesMultiple hosts
Sporozoan ProtozoansPlasmodium
Causes malariaMost widespread parasite of humansDisease in 515 million people
annually US population is 300 million 5 million infected with HIV annually
Kills 1-3 million people annually 2.8 million AIDS deaths annually
Transmitted by female Anopheles mosquito
No vaccine
Sporozoan ProtozoansToxoplasma gondii
May be 60 million infections in US
“Fecal-oral” route Cat feces contaminating hands,
water, or utensilsMost infections have no
symptomsSome people show flu symptomsImmunosuppression increases
infection risk
Sporozoan ProtozoansToxoplasma gondii (cont.)
Can cause serious disease in fetus if mother infected ONLY if is mother’s first
exposureCan affect host behavior
May be a cause of schizophrenia
Cats shed cysts for a few weeks after first infection