StudySkills
lor Science
Chapter13
Protozoa
After readingthis chapteryou will be ableto:
l.
2
describeprotozoain general
discussthe 1yo 1y,p,9;
of proto-a0..4;-amoebae
and citates
Protktsue organisms
thathavecharacteristics
simlarto bothplantsandanimals,but they
arenot animalsor plants. They aremostlyone-celledandbelongto Kingdomprotista.
hotozoa is one large group of protists. In this chapteryou will leam aboutprotozoain
generalandmorespecificallyabouttwo commontypesof prolozoa.
Protozoain General
A$pr9gqzoalharggg4eiDcharacteristigl.
First, theyareone-cclled,nongreen,animal-like
protists. Second,they can move aboutand are classifiedaccordingto how they move.
Third, protozoamust sec-ure..their
own food and are speciallyequipped0o.doso. Most
protozoaac,tiv-_elJ-E3g-ftstf.Opd.
They get it from thesurroundingwater.andconsumeit
inchunks'Somgprotozoa,however,ar-eper--asites.
Theylivedirectlyoffotherorganisms.
Amoebae
Formingpseuilopodia.Oneof thesimplestprotozoans
is thealooeba,-Amoebae
areunique
in how they move. To move, theydeveloppseudopodiapseud,opodiaarefalsefeetformed
by flexibleplasmamembranes^and
cytoplasm.Theformationof psqudopodia
involvescertain
stages.Initially, thecytoplasniis in a fixed,gelatinousstate.ThEr,chemicalchanges
cause
partof ttrecytoplasmto becomea fluid. This fluid, whichis like 41ruesolution,is knownas
a sol. cyloplasm in a sol conditioncan-flowfreely. Next, cytoflasm flows into the cell
membrane,extendingit to form a pseudopodi.qr4.
pen this cfroplasmchangesbacklo-a&e.!
Finally, other areasof the cytoplasmundergothe dme sol-ge-ltransformationforming new
pseudopodia.New pseudopodiaareformedand othersdisappear.In this way, ttreshapeof
amoebae
changesconstantly.SeeFigurel3J.
337
338
Chapten
Sample
Figure13-1.Movementof the Amoeba
.
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g jZt
"
Whetheran amoebamovesas a resultof a
o u s ho r a p u r r sI nd o u b l
^\'
Jr.,andRobertC.Smoot,
F.Oram,PaulI' Hummer,
From:Raymond
MerrillPub.
(Columbus,
Ohio: Charles
Biology:Living Systems
of thepublisher'
by permission
Co.,1976),p. 327.Reprinted
in gettingfoodaswellasin movingabout'
Fooil-gettingstfuctures.Pseudopodiaareused
Pseudopodiaengulf particlesof food. The food particlesenterthe cytoplasmwherethey
aredigested.You canseethe food vacuolesin which digestiontakesplace. SeeFigure
t3-2.
Figurel3-2. Food-GettingStructuresof the Amoeba
Pseudopodia
Habitat. Thekind of amoebastudiedin thelaboratoryis commonlyfoundin pondsand
however,are
otherbodiesof water. This typeof amoebais harmless.Someamoebae,
to humans'
andale quitedangerous
water.Theycancausedisease
foundin contaminated
$udySkills
forScience
Ciliates
Generaldescripdott.ciliates, anothercommonprotozoa,
haveseveralcharacteristics.
First, they areone-celredprotozoalike amoebae.
Second,they havea definite shapewittr
a stiff coveringborderingtheir cells, unlike amoebae.
The stiff coveringwhich borders
cellsof ciliates is callel apellicle. Third, on their
surfacesthey havehair-lik e cilta. cilia
, are hairlike structtlresusedfor getting food
and for moving about.
Parameciumone groupof ciliatesoftenstudied
by biologystudentsis theparamecium,
which hascertaincharacteristics.
First, a parameciumis a complexorganismin
which
differentpaftsof thecytoprasmdo differentjobs.
second,a parameciumhastwo typesof
nucleiwithinasinglecell.
Thereisalargemicronucleuswhichcontrolsthebasicactivities
of thecell. In addition,there'sa smallermicronucleus
whichis involvedin reproduction.
Both nucleihelpconnol large,complexciliates.
SeeFigurel3_3.
Figurel3-3. paramecium
SftX'#fTj;;,K
Btrnad.coordinator,
Bio-r.raming
center,
Third,a paramecium
movesby beatingn, .'a on irssurface.Thecengrides
rapidly
throughwater'usuallya paramecium
rotates
asit moves.seeFigurel3-4.
339
Chapters
340 Sample
Figure134. Rotating Movement
F. Oram,PaulI. Hummer,Ir.' andRobertC'
From:Raymond
Ohio: Charles
Smoot,Biblogr: Llvlng Systems(Columbus,
of the
by permission
Merrill Pub.C6.,tSZe),p. f28. Reprinted
publisher.
Summary
hotozoa areone-celled,nongreen,animal-likeprotists.Theamoebais oneof thesimplest
protozoans.
Amoebaeformpseudopodiaorfalsefeetusedformovingaboutandforgetting
food. More complexprotozoaareciliates. Ciliates havehairlike cilia on their surfaces
usedfor getting food and for moving about. Parameciumis a familiar ciliate. There is
jobs.
division of labor within its cell. Different partsof its cyoplasm do different
Exercises
How doeSttreamoebamove?
2, De,scribethe sol-gel transformationin the amoeba.
3. Whatarecilia?HowaretheYused?
4. Why do you think two nuclei may be necessaryin a paramecium?
l.
Suggestionfor Further Reading
Guttman,Buron S. andHopkins,JohnsW. UnderstandingBiology'
Orlando: HarcourtBraceJovanovich,Inc.,1983.