Eukaryotic flagella and cilia
Download as DOCX, PDF0 likes57 views
. Cilia and flagella are the most prominent organelles associated with motility. 2. both are whip like and beat to move the microorganism they differ from one another in two ways. cilia and flagella are very similar in ultrastructure. 3. First, cilia are typically only 5 to 20 m in length, whereas flagella are 100 to 200 m long. 4. Second, their patterns of movement are usually distinctive. 5. Flagella move in an undulating fashion and generate planar or helical waves originating at either the base or the tip. 6. If the wave moves from base to tip, the cell is pushed along; a beat traveling from the tip toward the base pulls the cell through the water.
More Related Content
Similar to Eukaryotic flagella and cilia (20)
More from kamilKhan63 (20)
Recently uploaded (20)
Eukaryotic flagella and cilia
- 1. Eukaryotic flagella and cilia Ciliaandflagellaare the mostprominentorganellesassociatedwithmotility.Bothare whiplike andbeattomove the microorganismtheydifferfromone anotherintwoways.Ciliaandflagellaare verysimilarinultrastructure.First,cilia are typicallyonly5to 20 m inlength,whereasflagellaare 100 to 200 m long.Second,theirpatternsof movementare usuallydistinctive.Flagellamove inanundulatingfashionandgenerate planarorhelical wavesoriginatingateitherthe base or the tip.If the wave movesfrombase to tip,the cell ispushedalong;a beattravelingfromthe tiptowardthe base pullsthe cell throughthe water. Sometimesthe flagellumwill have lateral hairscalledflimmerfilaments(thicker,stifferhairsare calledmastigonemes). These filamentschange flagellaractionsothat a wave movingdownthe filamenttowardthe tippullsthe cell along insteadof pushingit.Sucha flagellumofteniscalledatinsel flagellum, whereas the nakedflagellumisreferredtoasa whiplashflagellum. Cilia,onthe otherhand,normallyhave a beatwithtwodistinctive phases.The ciliumstrokesthroughthe surrounding fluidlike anoar,therebypropellingthe organismalonginthe water.Thiscoordinationallowsthe organismtomove smoothlythroughthe water.Theyare membrane-boundcylindersabout0.2 m indiameter.Locatedinthe matrix of the organelle isacomplex,the axoneme,consistingof nine pairsof microtubuledoubletsarrangedina circle aroundtwo central tubulesThisiscalledthe 9 - 2 patternof microtubules.Eachdoubletalsohaspairsof arms projectingfrom subtubule A (the completemicrotubule) towardaneighboringdoublet.A radial spoke extendsfromsubtubule A toward the internal pairof microtubuleswiththeircentral sheath. These microtubulesare similartothose foundinthe cytoplasm.Eachisconstructedof two typesof tubulinsubunits, - and -tubulinsthatresemble the contractile proteinactinintheircomposition. A basal bodyliesinthe cytoplasmatthe base of eachciliumorflagellum.Itisashort cylinderwithnine microtubule tripletsarounditsperiphery(a90 pattern) and isseparatedfromthe restof the organelle byabasal plate.The basal bodydirects the constructionof these organelles.Ciliaandflagellaappeartogrow throughthe additionof preformedmicrotubule subunitsattheirtips. Ciliaandflagellabendbecauseadjacentmicrotubuledoubletsslidealongone anotherwhile maintainingtheirindividual lengths. The doubletarmsabout 15 nm longare made of the proteindynein.ATPpowersthe movementof ciliaandflagella,and isolateddyneinhydrolyzesATP.Itappearsthatdyneinarmsinteractwiththe B subtubulesof adjacentdoubletstocause the sliding.The radial spokesalsoparticipateinthisslidingmotion.Ciliaandflagellabeatata rate of about10 to 40 strokesor wavespersecondandpropel microorganismsrapidly. The record holderisthe flagellateMonasstigmatica,whichswimsata rate of 260 m/second(approximately40cell lengthspersecond);the commoneuglenoidflagellate,Euglenagracilis,travelsataround170 m or 3 cell lengthsper second.The ciliate protozoanParameciumcaudatumswimsatabout2,700 m/second(12 lengthspersecond).Such speedsare equivalenttoormuch fasterthanthose seeninhigheranimals,butnotas fastas those inprokaryotes.