Plastids presentation

A detailed information about cell organelle- plastids.

1. CHARTHA . GAGLANI

2. CONTENTS
1.Introduction 4. Leucoplasts
2.Chromoplasts 5. Amyloplasts
•Appearance 6. Elaioplasts
•Structure 7. Proteinoplasts
•Function
3. Chloroplasts
•Structure
•Function

3. INTRODUCTION
•Theplastidisamembraneboundorganellefound
inthecellsofplants,algae,andsome
othereukaryoticorganisms.
•PlastidswerediscoveredandnamedbyErnst
Haeckel,butA.F.W.Schimperwasthefirstto
provideacleardefinition.
•Plastidsarethesiteofmanufactureandstorageof
importantchemicalcompoundsusedbythecells
ofautotrophiceukaryotes.

4. •Theyoftencontainpigmentsused
inphotosynthesis,andthetypesofpigmentsin
aplastiddeterminethecell'scolor.Theyhave
acommonevolutionaryoriginandpossessa
double-strandedDNAmoleculethatiscircular,
likethatofprokaryoticcells.

6. CHROMOPLASTS
•Chromoplastsareplastids,heterogeneousorga
nellesresponsibleforpigmentsynthesisand
storageinspecificphotosyntheticeukaryotes.

7. APPEARANCE
•Chromoplastsareplastidsthatarecoloreddue
tothepigmentsthatareproducedandstored
insidethem.
•Theyarefoundinfruits,flowers,roots,and
senescentleaves.
•Thecoloroftheseplantorgansisassociated
withthepresenceofpigments,apart
fromchlorophyll.

8. STRUCTURE
•Chromoplasts vary in structural appearance under
an electron microscope.
•They may generally be grouped into five types:
(1) globular, (2) crystalline, (3) fibrillar, (4)
tubular, and (5) membranous.
•Nevertheless, some chromoplasts may be harder
to classify when their structure is rather
complicated, such as those of tomatoes that
appear both membranous and crystalline in
appearance.

9. FUNCTIONS
•Chromoplastsarefoundinfruits,flowers,roots,
andstressedandagingleaves,andareresponsible
fortheirdistinctivecolors.
•Thisisalwaysassociatedwithamassiveincrease
intheaccumulationofcarotenoidpigments.
•Theconversionofchloroplaststochromoplasts
inripeningisaclassicexample.
•Theyaregenerallyfoundinmaturetissuesand
arederivedfrompreexistingmatureplastids.

10. •Chromoplastssynthesizeandstorepigmentssuchas
orangecarotene,yellowxanthophylls,andvariousother
redpigments.
•Themainevolutionarypurposeofchromoplastsis
probablytoattractpollinatorsoreatersofcoloredfruits,
whichhelpdisperseseeds.
•However,theyarealsofoundinrootssuch
ascarrotsandsweetpotatoes.
•Theyallowtheaccumulationoflargequantitiesofwater-
insolublecompoundsinotherwisewaterypartsofplants.

11. Tomato

12. PHAEOPLASTS
•Theseareyelloworbrownplastidsfoundin
brownalgae,diatomsanddinoflagellates.
•Fucoxanthinisacarotenoidpigmentwhich
masksthecolourofchlorophylla,whichis
alsopresent.
•Italsoabsorbslightandtransfertheenergyto
chlorophylla.

13. Brown algae Diatom
s
Dinoflagellates

14. RHODOPLASTS
•Theseareredcolouredplastids.Itisfoundin
redalgaeanditsredcolourisdueto
phycoerythrin.
•Italsoabsorbslight.

15. Red algae

16. CHLOROPLASTS
•Thechloroplast,foundonlyinalgalandplantcells,isacell
organellethatproducesenergythroughphotosynthesis.
•ThewordchloroplastcomesfromtheGreekwordskhloros,
meaning“green”,andplastes,meaning“formed”.
•Ithasahighconcentrationofchlorophyll,themoleculethat
captureslightenergy,andthisgivesmanyplantsandalgaea
greencolor.
•Likethemitochondrion,thechloroplastisthoughttohave
evolvedfromoncefree-livingbacteria.

18. STRUCTURE
•Chloroplasts,likemitochondria,areoval-shapedandhavetwo
membranes:anoutermembrane,whichformstheexternal
surfaceofthechloroplast,andaninnermembranethatliesjust
beneath.
•Betweentheouterandinnermembraneisathin
intermembranespaceabout10-20nanometerswide.
•Thespacewithintheinnermembraneiscalledthestroma.
•Whiletheinnermembranesofmitochondriahavemanyfolds
calledcristaetoabsorbsurfacearea,theinnermembranesof
chloroplastsaresmooth.
•Instead,chloroplastshavemanysmalldisc-shapedsacscalled
thylakoidswithintheirstroma.

19. •Inthestroma,enzymesmakecomplexorganic
moleculesthatareusedtostoreenergy,suchas
carbohydrates.
•ThestromaalsocontainsitsownDNAand
ribosomesthataresimilartothosefoundin
photosyntheticbacteria.
•Forthisreason,chloroplastsarethoughttohave
evolvedineukaryoticcellsfromfree-living
bacteria,justasmitochondriadid.

21. FUNCTION
•Chloroplastsarethepartofplantandalgalcellsthatcarryout
photosynthesis,theprocessofconvertinglightenergyto
energystoredintheformofsugarandotherorganicmolecules
thattheplantoralgausesasfood.
•Photosynthesishastwostages.
•Inthefirststage,thelight-dependentreactionsoccur.
•Thesereactionscapturesunlightthroughchlorophylland
carotenoidstoformadenosinetriphosphate(ATP,theenergy
currencyofthecell)andnicotinamideadeninedinucleotide
phosphate(NADPH),whichcarrieselectrons.

22. •Thesecondstageconsistsofthelight-independent
reactions,alsoknownastheCalvincycle.Inthe
Calvincycle,theelectronscarriedbyNADPH
convertinorganiccarbondioxideandtoanorganic
moleculeintheformofacarbohydrate,aprocess
knownasCO
2fixation.
•Carbohydratesandotherorganicmoleculescanbe
storedandusedatalatertimeforenergy.

24. LEUCOPLASTS
•Leucoplastsareacategoryofplastidandassuch
areorganellesfoundinplantcells.
•Theyarenon-pigmented,incontrasttootherplastidssuch
asthechloroplast.
•Lackingphotosyntheticpigments,leucoplastsarenotgreen
andarelocatedinnon-photosynthetictissuesofplants,such
asroots,bulbsandseeds.
•Theymaybespecializedforbulkstorage
ofstarch,lipidorproteinandarethenknown
asamyloplasts,elaioplasts,orproteinoplasts(alsocalled
aleuroplasts)respectively.

25. Leucoplasts Potato

26. AMYLOPLASTS
•Amyloplastsareatypeofplastid,double-enveloped
organellesinplantcellsthatareinvolvedinvarious
biologicalpathways.
•Amyloplastsarespecificallyatypeleucoplast,a
subcategoryforcolorless,non-pigment-containingplastids.
•Amyloplastsarefoundinrootsandstoragetissuesand
storeandsynthesizestarchfortheplantthrough
thepolymerizationofglucose.
•Starchsynthesisreliesonthetransportationofcarbonfrom
thecytosol,themechanismbywhichiscurrentlyunder
debate.

27. Cotyledon

28. ELAIOPLASTS
•Elaioplastsareatypeofleucoplastthatisspecialized
forthestorageoflipidsinplants.
•Elaioplastshouseoilbodydepositsasrounded
plastoglobuli,whichareessentiallyfatdroplets.

29. Orchids
Lily
Oil droplets

30. PROTEINOPLASTS
•Proteinoplastsarespecializedorganellesfoundonlyinplantcells.
•Proteinoplastsbelongtoabroadcategoryoforganellesknownasplastids.
•Becausetheylackpigment,proteinoplastsaremorespecificallyakind
ofleucoplast.
•Theycontaincrystallinebodiesofproteinandcanbethesitesofenzyme
activityinvolvingthoseproteins.
•Proteinoplastsarefoundinmanyseeds,suchasbrazil
nuts,peanutsandpulses.
•Althoughallplastidscontainhighconcentrationsofprotein,proteinoplasts
wereidentifiedinthe1960sand1970sashavinglargeproteininclusions
thatarevisiblewithbothlightmicroscopesandelectronmicroscopes.

31. Seeds

32. THANK YOU…