lab10 algae

Concepts of Botany, Algae, page 1 of 21

BIOL221ConceptsofBotany Fall2010

AlgaeMembersoftheKingdomPlantaearenottheonlyorganismsthatarephotosynthetic.PhotosyntheticorganismsnotinthePlantKingdom,traditionallyreferredtoasalgaearetypicallyaquaticandmembersofthetraditionallyrecognizedeukaryoticKingdomProtista(whereallsimpleeukaryoticorganismsgo)ortheDomainBacteria.Thephylogenetictreebelowprovidesanoverviewofthemajorlineagesoflifeandhowtheyarethoughttoberelatedtooneanother:the7groupsnumberedbelowarethe7majorlineagesofphotosyntheticorganismsandtheyreobviouslynotallthatcloselyrelatedtooneanother.

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Adapted from Fig. 15-3 in Raven et al. (2007). A phylogenetic tree based on DNA sequences, showing 7 major groups of photosynthetic organisms.


Algae(orsingularalga)ishistoricallyatermappliedtoanunnaturalassemblageofphotosyntheticorganismsthatareusuallymorphologicallysimplerthanmembersoftheplantkingdom(theplantkingdomincludingbryotphytes,pteridophytes,andseedplants).Somealgaeareunicellular,butothersarelargerandmulticellularorganismsthatarecalledseaweeds.Withinthealgaeyoucanseethemajortrendintheevolutionarydevelopmentofmulticellularityreflectedinthediversityoforganismalforms:i.e.,unicellular>>filamentous(exhibiting1Dmulticellulargrowth)>>planar/thalloid(exhibiting2Dmulticellulargrowth)>>3Dformsthatbegintoresembleplantsintheircomplexity.Thisisimportantb/citisthisevolutionarytrendthatgaverisetotheKingdomPlantaefromamongstthegreenalgaeinparticular. Algaehavebeendividedintogroupsbasedmainlyondistinctiveplastidaccessorypigments.Becauseofthesepigments,manygroupsofalgaehavebeenknownbytheircolor:hencered,green,brown,etc.Modernclassificationsdelimitthemwithmanyothercharacterssuchascellwallcomponents,reproductivestructures,anddistinctivefoodstoragemolecules. Algaearethedominantproducersinaquaticenvironments,sotheyareveryimportantecologically.Thematerialsavailableinlabtodayrepresentthemajoralgaldivisions,alongwiththecyanobacteria.

SomeUsefulTermsforAlgaeinthislab:Bladderseepneumatocyst.Bladetheflattenedanalogofaleafinmanyseaweeds.Coenocyticanorganismwhosecell(s)containmultiplenuclei(e.g.,thealgaVaucheriaexistsasalong,sometimesbranchedfilamentthatisjustoneorfewgiantcells).Colonialanorganismactuallymadeupofmultipleorganisms.Inalgae,theseindividualorganismsaretypicallyunicellularandtheysticktooneanotherbyaspecialgelatinousmatrixtheysecrete.Eyespotapatchofpigmentonamembraneinsideacellthatcandetectlight.Thesearetypicallyredandfoundonlyinmotilealgaesincethecell,onceitdetectslight,canthemswimtowardsit(orawayfromitifitistoomuch).Filamentousanorganismthatislongandthin(sometimesbranching),andtypicallymadeupofastringofcells.Holdfastthebranchingstructureatthebaseofmanyseaweedsthatholdthemtoasubstate.Motiletohavedirectedmobility.Cellsabletopropelthemselvesbysomemeansaresaidtobemotile.Usuallythisisachievedbywayofaflagellumortwo(e.g.,Chlamydomonas).However,thefilamentouscyanobacteriumOscillatoriacanmovebywayoftheentirefilamentandmassoffilamentsoscillatingortwirling,anddesmidssuchasClosteriumcanmoveinasomersaultingmotionbysecretingjetsofmucilagethroughspecialporesinthecellwallalternatinglyfromdifferentendsofthecell.Pneumatocystanairfilledbladderlikeorganonmanyseaweedsthatfunctionforbuoyancytokeepthebladesafloatinapositiontointerceptsunlight.Pyrenoidscentersofcarbondioxidefixationorstarchsynthesiswithinthechloroplastsofalgaeandhornworts,visibleb/cofthedensityofenzymesinthatregion.Pyrenoidsarenotmembraneboundorganelles,butspecializedareasoftheplastidthatcontainhighlevelsenzymessuchasribulose1,5bisphosphatecarboxylase/oxygenase(RubisCO).Seaweedamacroscopicmarinealga.Thistermhasnorealtechnicaldefinitionandnotaxonomicsignificancesincesomeseaweedsaremorecloselyrelatedtounicellularormicroscopicalgaethantheyaretootherseaweeds.Stipethestalkbetweentheholdfastandthebladesofmanyseaweeds.


A.DichotomousKeytoFreshwaterAlgae .Usingthedetachablekeytofreshwateralgalgeneraonthelastpageofthislab,identifythe10unknownmonoculturesofalgaetotheirrespectivegenera. Thealgalsamplesinvials110arelargelymonocultures,butthepresenceofotherspeciesascontaminantsispossible.Oftentherearesmallprotozoa(microscopicanimals)feedingonthealgaeinthesevials,butdonotbedistractedbythem.Focusyourkeyingeffortonthemajorityalgaineachvial. Seeinstructorfortheanswersattheendofclass.Importantdetailsareviewedat200Xand400X(orhigher)magnifications.

0.Workinginpairs,makewetmounts(withcoverslips)oftwoofthenumberedalgaetubesatatimefromtheback.Besuretorememberwhichnumbereachslideisofperhapsbynumbertheslideswithtapeandpen. a.Dothisbyplacingadropontoslide(besuretogetsomealgaeinityoumayhavetoflush thetubeoncewiththepipette). b.Coverwithcoverslip(becarefullayingthecoverslipdownsoasnottodestroylargecolonial formssuchasVolvox). c.Donotletthesewetmountsdryoutuntilyouaredonelookingatthem.

1.Inspectthealgaforcolorsincethisisacharacteristicyoulloftenneedtoidentifythem.Dothisone(orboth)oftwoways: a.holdthetubeuptothelightoragainstwhitepaper. b.thenbesuretoconfirmthiscoloragainonceyouvegotitunderthescopesincesomeofthe tubeshavesoilcontaminantsinthemandwillmakealgaeinthetubelookbrownwhenthecells areactuallygreen,forexample.2.Workyourwaythroughthedetachablekeyonthelastpagetoidentifythegenus.YoumayvisitsectionCinthelabmanualwithinformationabouteachalgalgrouptoconfirmyourtentativeidentificationwithpicturesordescriptions.3.Makedrawingsbelowandlabelwithgenusname,themagnificationusedforthedrawing,andotherstructuressuchasCHLOROPLAST(S),FLAGELLUM(FLAGELLA),PYRENOID(S),EYESPOT,NUCLEUS,etc.Alsorecordthecolorofyouralgae,asseenwiththenakedeye.4.Aftermakingyouridentification,gotosectionCinthelabmanualonthegroupandanswerthequestions.


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B.OPTIONAL(perinstructorchoicedifficulttofindalgaeNovemberMarch):PracticalAlgalTaxonomyTaxonomyisthescientificdisciplinethatdealswiththeformalnaming,classification,andidentificationoforganisms.Ataxonomickey(whichyouusedabove)isaveryusefultoolthatbiologistsandpeoplewhomonitorwaterqualityusetohelpidentifywhichalgaearefoundgrowinginthebodiesofwatertheyareinterestedin.UsetheskillsfromPartBabovetoanswersomeofthesepracticalquestions.1.WhattypesofalgaeorcyanobacteriadogrowintheRoddyPond?Additionally,dodifferentspeciesgrowatdifferentdepths?Itisconceivablethatdifferentalgalspecieshavedifferentpreferencesinlightintensityandtemperatureandwewilltestthishypothesis.SamplefromRoddyPondthefollowing(notethatinwintermonths[novemberthroughMarch]mostofthealgaearelowinthewatercolumnoronthebottomneartheshoresincetheyarenotveryactiveinphotosynthesis).

1.Surface(thepondscum)2.Sampleat6inches(18cm)belowthesurface.3.Sampledeeper,between35feet(butdonotscrapethepondbottom).Youmayneed tosamplefromthepierforthisdeepersample.4.Placeintoglassjars/vialswithlidsandlabel.


5.Usethedetachabledichotomouskeytoalgaeandcyanobacteriaonthelastpageto identifysamplesofphotosyntheticorganismstakenfromthepond.2.IsRoddyPondsafeforcattleorcowstodrinkfrom?Farmerssometimeshavemajorproblemswithcattledrinkingfrompondswithhighdensitiesofcyanobacteria(seethesnippetofthe1999articlebyCoddetal.onthenextpage).Althoughcyanobacteriaresemblealgae,theyarebacteriaandmanycyanobacterialspeciesmakepotentneurotoxinsthatcankillcattle.Youcanusethedetachabledichotomouskeytoalgaeandcyanobacteriaonthelastpagetoidentifysamplesofphotosyntheticorganismstakenfromthepond.Pretendyouareafarmer,andifyoufindcyanobacteriaingreatabundance,thenyoumayhavecauseforconcern.

C.GroupsofCyanobacteria&Algae Regardlessofwhetherornotyouveseenlivingexamplesinlabtoday,readeachsectionandanswerthequestions.C1.Group1:Cyanobacteria(bluegreenalgae)Cyanobacteriaarephotosyntheticbacteriaandweresometimescalledbluegreenalgaebyearlierbotanists,buttheyareverydifferentthantheotherorganismswetypicallycallalgae.Thatis,cyanobacteriaareprokaryotes(i.e.,theylackanucleusandmembraneboundorganelles).Whereasplantsandotheralgaehavechloroplastsintheircellstocarryoutphotosynthesis,thewholecellofacyanobacteriumishomologoustoachloroplast.Likeotherprokaryoticcells,thecellsofcyanobacteriaaremuchsmallerthaneukaryoticcells.Althoughcyanobacteriahavechlorophyll,theirdifferentmixofaccessorypigmentsmakethemappearbluishgreen.Manyareunicellular,othersarefilamentous,whileothersarecolonial. 1.Thoughtquestion:Ifyouweretohaveafilamentous(orunicellular)cyanobacterium andafilamentous(orunicellular)alga,howmightyoutellthemapart?Listatleasttwo ways,basedonyourreadingoftheaboveparagraph.


2.OneoftheunknownsamplesfromsectionBwasOscillatoriaorLyngbya,whichhave filamentswhichcanmoveoroscillate,causingthemassoffilamentstomove!

Didyouseeevidenceforthat? Whatcolorwerethemassesoffilamentinthestockculturetubesorunderthe microscope?

3.WhichothergeneraofcyanobacteriadidyoufindinthemysterymonoculturesinpartA? CrossreferencetheseanswerstoyourdrawingsinpartAabove.

Above:Cyanobacterialgenera.

Figure at left: some cyanobacteria. A-B and D-E are more or less colonial, since the cells and/or filaments stick together in a gelatinous matrix.


C2.Group2:Dinoflagellates .Dinoflagellatesarenotbacteriabutunicellularprotists(i.e.,intheKingdomProtistaaccordingtoa5or6kingdomclassificationscheme). Thus,aredinoflagellatesprokaryotesoreukaryotes?Wedonothavedinoflagellatesinanyofthemonoculturesinlabtoday,butRoddyPondsometimeshasdinoflagellatesinit(note:yourparticularlabmaybetooearlyintheseasontoseeany).Ifthereareanysampledinyourpondwater,youwillknowadinoflagellatebyitsolivebrowncolor(dueinparttoaccessorypigmentsPERIDININorFUCOXANTHIN)andtheirelaborateshapesandornamentation.Interestingphenomenainnatureincludebioluminescenceandredtidescausedbysomemarinespecies.

Howmanycellsiseachdinoflagellate?Inspectyoursamplesandthepicturesbelow:Howmanyflagelladothesehaveandhowiseacharrangedtohelpthemmove?Readinyourtextbookaboutthearmororplates(p.334).Aretheplatesinsideoroutsidethecell(s)?Whataretheymadeof?Howisthisthesameordifferentthanacellwall?

Figureabove:Variousformsofdinoflagellates.


C3.Group3:Euglenoids .EUGLENA:PLANTORANIMAL?RemoveadroportwoofthefreshwatersamplecontainingEuglenagracilisEuglenagracilisisjustoneofmany(ca.800900)unicellularspeciesofthegenusEuglena.Theydonothavecommonnameslikebirdsortrees,sowehavetorefertothembytheirscientificnameEuglena.Euglenaareinterestingbecausetheycombinesuperficialcharacteristicsofbothplantsandanimals.Theycanmaketheirownfoodlikeaplant,throughphotosynthesis,buttheycanalsoeatotherthings,likeananimal(althoughtheyactuallyeatmorelikeanamoebathroughphagocytosisthanananimal).Theycanalsoswimandmovethankstotheirflagellum.ScientistsarguedforyearsaboutwhichKingdomtoputthemin:AnimaliaorPlantae?Rightnowtheyareinneither:accordingtosomeclassificationstheyareintheKingdomProtistawithothersimple(oftenmicroscopic)eukaryotes,suchasamoebaandparamecium.Protistsareeukaryotes,typicallysmallormicroscopic,whichlacksufficientcharacteristicstootherwisejustifytheirinclusionintheanimal,plant,orfungalkingdoms.Aeuglena'sbodyisunicellular.Theoutermostenvelopeistheplasma(cell)membrane,beneathwhichliesthepellicle(amatrixofproteinbandsthatspiraldownthelengthofthecell).Thepelliclehelpstheeuglenamaintainitsdistinctiveshape,althoughitisquiteflexibleandcanbeflexedbythecellinaninchwormtypefashion.Euglenatypicallystoretheirexcesscarbohydratesasparamylon(apolymerofglucoserelatedtostarch),distributedthroughoutthecytoplasmasparamylonbodies.Theirchloroplastpigmentprofileissimilartothatofgreenalgaeandplants:chlorophylla,b,andcarotenoids.Atoneendofacellisacontractilevacuole,whichhelpsexpelexcesswaterabsorbedbythecellfromitsfreshwaterenvironment.


Sometimes,sincetheyliveinwater,iftherearemillionsofeuglenatogether,theyformamatonthesurfaceofapondormarshthatyoucansee.Itlooksslimy,alotlikealgae.Somepeoplesayitlookslikepeasoup.Euglenagetintoswimmingpoolstoo,iftheyarenotcleanedregularly.

1.Areeuglenaunicellularormulticellular?2.Areeuglenaanimals,plants,protists,orbacteria?Prokaryoticoreukaryotic?3.Whatorganellecarriesoutphotosynthesis?4.Areeuglenaautotrophicorheterotrophic?Explain.5.Howmanyflagelladidtheeuglenafromtheunknownalgalculturesabovehave?6.Doestheflagellumorflagellaworkbypullingorpushingthecellthroughthewater?

7.Whatistheeyespotusedfor?8.Whatisthefunctionofthenucleus?10.Whatisthefunctionofthecontractilevacuole?Whatwouldhappenifthecelldidnothavethisorganelle.11.DidtheshapeofEuglenacellschangewhileyouobservedthem?Orweretheyrigid?


C4.Group4:Brown,Goldenbrown,andYellowbrownAlgae .Adiversegroupunitedbytheaccessorypigmentfucoxanthinandcarbohydratereserveslaminarinortheverysimilarchrysolaminarin. C4.1.Diatoms

Diatomsareunicellularorcolonialorganismsthatareexceedinglyimportantcomponentsofphytoplanktonofbothmarineandfreshwatersystems.Inadditiontotheirchlorophyll,diatomchloroplastscontaintheaccessorypigmentfucoxanthin,andthechlorophyllplusfucoxanthinmakesthemappeargoldenbrownorbrownyellowincolor.Theircarbohydratereservesareintheformofchrysolaminarin,astarchrelative.FossilevidenceindicatesthattheyevolvedduringorbeforetheJurassic.Fossilbedsofdiatomsareoftencalleddiatomaceousearth,whichisoftenusedbyhumansasawaterfiltermatrix(e.g.,poolwaterfiltersareoftendiatomaceousearth),orasapolishingagent.Inthestationintheback,wehaveasampleofdiatomaceousearth(i.e.,diatomfossils).Muchofouroildepositsinworldarethetransformedorganicremainsofdiatomsandothermarinealgae.

Diatomslackflagellaandarenonmotile.Outsideoftheplasmamembraneliesthecellwall,whichconsistsoftwohalvesmadeofhydratedsilicadioxide.ThecellwallofdiatomsiscalledafrustuleandthetwohalvesfittogetherlikeaPetridish.Thesefrustulesareveryornateandtheseornamentationsareusedtodistinguishspecies.Biotechnologistshavebeguntolookatmanipulatingdiatoms(throughartificialselection)toproducenanotechvalvesfornanoscaledrugdelivery,etc.

Above,scanningelectronmicrographsofawholediatom(left)andthehalfofafrustule,showingtheinsideface(right).


Above,Tabellariafromafreshwaterpond.

Above:Navicula(left)andSynedra(right).(http://biology.missouristate.edu/phycology)

Fig.1520afromRavenetal.(2007).Anartfulrepresentationofmanydifferenttypesofdiatoms.


C4.2.BrownAlgaeWhenmarinealgaegetbig(macroscopic),theyarecalledseaweeds.Mostbrownsarerelativelybig,andallaremulticellular.Only6of265generaoccurinfreshwater.Althoughtheyhavechlorophyll,theirspecialcarotenoidfucoxanthin(whichtheysharewithdiatomsandmanydinoflagellates)impartabrowncolortothem.Thesealgaestoreexcesscarbohydratesintheformoflaminarin,arelativeofstarchthatisverysimilartochrysolaminarinofdiatoms.Brownalgaehavecellulosiccellwalls.WellknownmembersincludeFucus(rockweed),LaminariaandMacrocystis(thekelps).CommonstructureswillincludeaHOLDFAST,aSTIPE,ABLADDER(forbuoyancy;akapneumatocyst),andBLADEStofunctionlikeleaves.

HoldfastLogicQuestion:Inwhatway(s)doholdfastsresembleroots,andinwhichway(s)dotheynot?HINT:thinkaboutfunction(s).


Above:Fucus,illustrationsoftheplant,aswellasthereproductiveparts.

A. Fucus, plant with receptacles and air bladders.

B. x-section of receptacle and smaller conceptacles.

C. Male conceptacle with antheridia. D. Antheridia with sperm.

E. Female conceptacle with oogonia. F. Oogonium with eggs.

Air bladder or receptacle?

Air bladder or receptacle?


C4.5.Group5:Glaucophytes .Extremelysmallgroupofalgaecloselyrelatedtoredandgreenalgae.Willnotbecoveredinlab.C4.6.Group6:RedAlgae .Theredalgaearelargelymarineandmulticellularseaweeds.Aclassofaccessorypigments(phycobilins)makesthemreddish.Redalgaestorecarbohydratesasflorideanstarch,astarchrelative.Redalgaehavecellulosiccellwalls.Wedonthaveanylivingredalgaeinthelab.Thereareherbariumspecimensforyourobservations,however.C4.7.Group7:GreenAlgae .Thegreenalgaeareaverylargeanddiversegroup.TheyrangefromunicellularorganismssuchasChlamydomonasorChlorellatocolonialorganismssuchasVolvox,tomulicellularorganismssuchasUlva(sealettuce)andChara(stonewort).Greenalgaesharewithplantsthesamechloroplastpigmentprofile(chlorophylla,b,andthecarotenoidsbetacaroteneandxanthophylls).Whenacellwallispresent,itiscellulosic.Manyoftheunlabeledmonoculturesofalgaeinthelabweregreenalgae.Presumably,youhavenowidentifiedthemall. C4.7A.Unicellularforms:allthreeofthealgaebelowwererepresentedintheunknownalgalcultures.Whichnumberswerewhich? Chlamydomonas,Chlorella,andClosterium

Above:Closterium.Thisunicellisbilaterallysymmetric,withtwoequalhalvesandasinglechloroplastin

eachhalf;suchunicellularalgaewithsymmetricalhalvesarecalleddesmids.Likemanydesmids,Closteriumcanmoveinasomersaultingmannerbysecretingmucilagefromalternatingendsofthecell

throughspecialporesinthecellwall.(http://silicasecchidisk.conncoll.edu/LucidKeys/Carolina_Key/html/Closterium_Main.html)

Whichofthealgaeaboveisanindicatorofpollutedfreshorsaltwaters?Seetheposterinthebackorsideoftheroom.

Terminal vacuoles contain crystals of barium or calcium sulfate. They vibrate due to Brownian motion. Function unknown.

Central nucleus.

Pyrenoids.


Above:LifecycleofChlamydomonas,aunicellulargreenalga.

C4.7B.Colonialforms:e.g.,Volvox&Pediastrum(sometimesfoundinthepond).CanyourecognizeVolvoxonsight?(Seefigurebelow.)

Above:Volvoxwithdaughtercoloniesinsidelargerparentcolonies.


Above:Pediastrum,aplatelikecolonialfreshwater(pond)alga.


C4.7C.Filamentousforms:Spirogyrawasrepresentedinthealgalculturesandpossiblythe pondwater.HowaboutOedogonium? WhyisSpirogyranamedassuch? Canyouspotpyrenoids(proteinrichsitesofcarbonfixationandstarchsynthesis)in Spirogyrachloroplasts? Howdoyoudistinguishthesetwogenera(lookatthekeyorthefigurebelow)?

Above,lifecycleofthegreenalgaOedogonium.


C4.7D.Macroscopic(seaweed)forms:seepictures,postersandherbariumspecimensatstationsaroundtheperipheryoftheroom.


Dichotomous Key to Some Freshwater Algal Genera ( 2010, MU Botany) 1. Alga unicellular and cells round, ovoid, or elliptic (cells may be clumped together but do not confuse this with a colony- which should be regular and ordered- or a filament).........................2 1. Alga colonial or filamentous (if colonial, then cells regularly and orderly grouped into spherical clusters or clusters of 2-4 cells).................................................................................... 7 2. Cells light golden-brown with highly transparent glass-like cell walls, shape elliptic (football-shaped) or long, thin and bone-shaped or rectangular, non-motile (Diatoms)..................................... 3 2. Cells bright-green; round, ovoid, or slightly crescent-shaped; motile or non-motile....................................... 4 3. Cells elliptic (football-shaped) or oblong (ends tapering)....................... Synedra (Diatom) 3. Cells rectangular or bone-shaped (ends blunt or bulbous)..................... Tabellaria (Diatom) 4. Cells narrow (longer than wide, although sometimes changing shape).. 5 4. Cells rounder or more ovoid.................................................................... 6 5. Cells apparently non-motile; very thin, with pointy ends, slightly crescent-shaped, with two equal halves the nucleus in the middle and each half containing one chloroplast................................... Closterium (Desmid Green Alga) 5. Cells motile; not so thin and with rounded ends; patch of red pigment near flagellum insertion................................................................. Euglena (Euglenoid) 6. Cells ovoid, usually rather motile, with a groove on the narrower end where two flagella insert; red eye-spot present........................................... Chlamydomonas (Green Alga) 6. Cells round, not apparently motile (not flagellate), no red eye............. Chlorella (Green Alga) 7. Alga colonial - cells grouped into groups of 2-4 cells or globular clusters, & held together by gelatinous matrix............................................ 8 7. Alga a filament, branched or not............................................................. 9 8. Colonies of 2-4 cells, cells blue-green.................................................... Eucapsis (Cyanobacterium) 8. Colonies round, some cells golden-brown-green.................................... Synura (Golden-Brown Alga) 9. Cells blue-green (Cyanobacteria)............................................................ 10 9. Cells or chloroplasts green or yellow-green............................................ 12 10. Filaments unbranched and straight or arching for long stretches........ 11 10. Filaments branched frequently and noticeably curved......................... Tolypothrix (Cyanobacterium) 11. Filaments with constrictions between the cells..................................... Anabaena (Cyanobacterium) 11. Filaments without constrictions between the cells; moving............... Oscillatoria (Cyanobacterium) 12. Filament branched and apparently coenocytic (all one cell or very few cells that is, with few or no internal partitions)....................... Vaucheria (Yellow-Green Alga) 12. Filament obviously multicellular........................................................... 13 13. Chloroplast(s) in each cell not round, instead somewhat coiled.. Spirogyra (Green Alga) 13. Chloroplast(s) round................................................................. Oedogonium (Green Alga)

lab10 algae

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