IiChloroplasts Ziyi-organelles ezibalulekileyo kwaye zizodwa kwiiseli zezityalo kunye neentlobo ezininzi ze-algae, isakhiwo kunye nokusebenza kwazo kube ngundoqo ekuphuhliseni ubomi emhlabeni. Ngokukwazi kwazo ukuguqula ukukhanya kube ngamandla ekhemikhali asebenzisekayo, iikloroplasts azixhasi nje ukukhula kwezityalo kunye nemetabolism kodwa zikwavumela ubukho bokutya okuninzi kwihlabathi liphela. I-morphology yazo, imisebenzi, amandla eseli, kunye nokuntsokotha kwemfuza kuzenza zibe yenye yezona zinto zinomdla kwaye zifundisiwe kwiseli yesityalo.
Iimpawu eziqhelekileyo kunye nenkcazo yekloroplasts
I-Chloroplasts zi-organelles ezinkulu ngokwentelekiso ngaphakathi kweeseli zesityalo, ngokuqhelekileyo ziqala ngobukhulu ukusuka kwi-1 ukuya kwi-10 ye-micrometer ubude. Ngokuxhomekeke kuhlobo lweeseli kunye neentlobo, iseli yesityalo, ngakumbi kumagqabi, inokuqulatha phakathi kwe-20 kunye ne-100 chloroplasts, ebonisa ukubaluleka kwazo kwiinkqubo ze-metabolic.
Ubukho bazo bulinganiselwe kwiiseli ze-photosynthetic eukaryotic, ezifana nezityalo kunye neentlobo ezininzi ze-algae, nangona kukho iinkqubo ezingaqhelekanga, ezifana ne-kleptoplasty, apho ezinye izilwanyana zinokufaka okwethutyana ii-chloroplasts ezivela kwizinto eziphilayo zezityalo kwiiseli zazo.
Ezi organelles ziyinxalenye yentsapho ye-plastid, iintlobo ze-organelles ezihambelanayo ezenza imisebenzi eyahlukeneyo efana nokugcinwa kwezinto, i-pigment synthesis, kunye nombono womxhuzulane, phakathi kwabanye. Phakathi kweentlobo ezahlukeneyo zeplastids, i ii-chloroplast Bagqama ngokuqulatha chlorophyll, i-pigment evumela ukuba babambe ukukhanya kwelanga okuyimfuneko ifotosinthesis.
Ubume kunye ne-morphology ye-chloroplasts kwizityalo
I-morphology ye-chloroplasts Iyaguquguquka kwaye ixhomekeke kuhlobo lweeseli kunye neentlobo, kunye nokusingqongileyo kunye nemiba yemfuza. Ngokuqhelekileyo zifumaneka kwiifom ze-oval okanye ze-disc-shaped, nangona kukho i-star-shaped, i-ribbon-shaped, kunye ne-morphologies enzima ngakumbi, ngakumbi kwi-algae. Ezi zimilo zinokutshintsha ekuphenduleni iimeko ze-osmotic kunye nesenzo se-mechanosensitive ion channels, ukulungelelanisa iimfuno zeselula.
- Imvulophu yeChloroplastidic: IiChloroplasts zisikelwe umda ngu a inwebu kabini (i-enveloped), eyenziwe yinwebu yangaphandle kunye nengaphakathi, eyahlulwe yi-intermembrane space. I-membrane yangaphandle ingena kakhulu ngenxa yobukho be-porins, ngelixa i-membrane yangaphakathi ilawula ngokungqongqo ukuhamba kweemolekyuli.
- Thylakoids kunye negrana: Ngaphakathi, ii-chloroplasts zinothungelwano oluntsonkothileyo lweenwebu ezenza iingxowa ezisicaba ezibizwa ngokuba thylakoids. Ezi zinokuqokelelwa zibe zizakhiwo ezibizwa ngokuba ingca (isinye: igranum), edityaniswe omnye komnye ngezandiso ze-membranous ezibizwa ngokuba yi-lamellae. Kukwiinwebu zethylakoid apho i i-photosynthetic pigments (i-chlorophyll, i-carotenoids kunye ne-xanthophylls) kunye neeprotheni ezenza ikhonkco lokuthutha i-electron.
- Stroma: Indawo yangaphakathi engahlaliyo yi-thylakoids ibizwa istroma, i-matrix apho i-DNA ye-setyhula ephindwe kabini ye-chloroplast, i-ribosomes ye-bacterial (70S), inani elikhulu le-enzymes kunye nezakhiwo zokugcina ezifana ne-starch granules kunye ne-lipid droplets (plastoglobules) zikhoyo.
- Amanye amacandelo: I-Chloroplasts iqulethe imimandla ekhethekileyo okanye i-subcompartments apho iiprotheni ezithunyelwa ngaphandle zingaqondiswa: i-envelope membrane, i-intermembrane space, i-stroma, i-thylakoid membrane, kunye ne-thylakoid lumen.
Ukuthelekisa nezinye ii-organelles, ezifana ne-mitochondria, kubonisa ukuba i-chloroplast inamacandelo amathathu amakhulu (isithuba se-intermembrane, i-stroma kunye ne-thylakoid lumen), xa kuthelekiswa nezimbini ze-mitochondria, ebonisa ukuntsokotha kwayo.
I-Cell dynamics: ukwahlukana, intshukumo kunye nokuziqhelanisa
Inani kunye nokuhlelwa kweekloroplasts azilungiswanga. Ukwahlulwa kwekloroplasts Kwiseli yesityalo, ilawulwa yinucleus yeseli kunye nelungu ngokwalo. Kubalulekile ukuba iiseli zentombi zifumane isixa esaneleyo sekloroplasts emva kwe-mitosis, kwaye iqhelana nokukhula kweseli kunye neemfuno zemetabolism.
Kwezinye iintlobo ze-algae, ulwahlulo lwe-chloroplast ludityaniswa kunye nolwahlulo lweeseli, ngelixa kwizityalo eziphakamileyo, ukulawulwa kuyinkimbinkimbi kwaye kunokuxhomekeka kubungakanani beseli kunokuzahlula ngokwawo. Ngokukodwa kwi-mesophyll yegqabi, ubuninzi be-chloroplast bunxulumene nommandla wamagqabi kunye nokuvezwa kokukhanya.
Olu lwahlulo lubandakanya ukwakheka kwezangqa zeprotheyini: engaphakathi (eyenziwe ngeeprotheyini ezidityaniswe kwikloroplast) kunye nengaphandle (eyenziwe ngeeproteni zenyukliya, ezifana nedynamin). Zombini zixhunyiwe kwaye zilungelelanise ngokuchanekileyo i-fission ye-organ.
Ukwengeza, iikloroplasts zinokuhamba ngaphakathi kweseli, uphawu olubavumela ukuba baziqhelanise nokutshintsha kweemeko zokukhanya. Ngaphantsi kokukhanya okukhulu, bahoxisa kwiindawo ezivezwe kakhulu ukuze bazikhusele; phantsi kokukhanya okuphantsi, zifudukela kwimimandla apho ukwamkela ukukhanya kusebenza ngokufanelekileyo. Le ntshukumo, enokufikelela kwizantya ezimalunga ne-1 µm/minute, ixutyushwa yi-actin filaments kunye ne-motor proteins kwaye isabela kwimiqondiso evela kwi-photoreceptors zombini kwi-plasma membrane nakwi-chloroplast ngokwayo.
Imisebenzi yekloroplasts: ngaphaya kwephotosynthesis
El eyona ndima ibalulekileyo yekloroplasts yi ifotosinthesis, inkqubo evumela izityalo ukuba ziguqule amandla okukhanya zibe amandla ekhemikhali agcinwe kwiimolekyuli eziphilayo. Nangona kunjalo, ii-chloroplasts zenza eminye imisebenzi emininzi ebalulekileyo:
- Iphotosynthesis: Le nkqubo inezigaba ezibini eziphambili:
- Isigaba sokukhanya: Kwenzeka kwiinwebu ze thylakoid. Ukukhanya kwelanga kuvuyisa i-chlorophyll kunye nezinye ii-pigments, ezikhuthaza ukuhamba kwee-electron ngokusebenzisa ikhonkco lokuthutha, ukuvelisa i-ATP kunye ne-NADPH, kunye ne-oksijini yemolekyuli (O2) njengemveliso ye-photolysis yamanzi.
- Isigaba esimnyama okanye umjikelo kaCalvin: Kwenzeka kwistroma. Isebenzisa i-ATP kunye ne-NADPH eyenziwe kwisigaba sokukhanya ukulungisa i-CO2 atmospheric kwaye ukuguqula ibe iswekile elula (triose phosphate) usebenzisa enzymes ezifana I-RUBISCO.
I-Genetics kunye nentsebenziswano ye-nucleus-chloroplast: ukuthengiswa kweeprotheyini
El chloroplast genome Ibhaktheriya ngokwendalo, ilifa elithe ngqo kwimvelaphi yayo ye-endosymbiotic. IneDNA ejikelezayo edibanisa phakathi kwama-200 nama-300 emfuza, enoxanduva lokudityaniswa kwezinto ezibalulekileyo, ezifana neeyunithi ezisembindini we-photosystems, i-ribosomal RNA, kunye nokudluliselwa kwe-RNA.
Nangona kunjalo, uninzi lweeprotheyini ezifunwa yi-chloroplast zifakwe kwi-nucleus yeseli kwaye kufuneka zingeniswe ngaphandle ngee-complexes ezikhethekileyo kwiinwebu zemvulophu (ebizwa ngokuba yi-envelope). tok y TIC kwi-membrane yangaphandle nangaphakathi, ngokulandelanayo). Iiprotheyini zeNyukliya eziya kwikloroplast zithwala i-peptide yomqondiso (i-peptide yokuhamba), ebonwa zezi zixhobo kwaye isuswe kanye ngaphakathi kwi-stroma, ivumela ukugoqa okufanelekileyo kunye nokusebenza kweprotheni ephuma kumazwe angaphandle.
Iiprotheyini zinokujoliswa kwiindawo ezithile ngaphakathi kwekloroplast: i-membrane yemvulophu, i-stroma, i-membrane ye-thylakoid, okanye i-lumen ye-thylakoid. Oku kurhweba ngokungekho mthethweni kubalulekile ekusebenzeni okufanelekileyo kwekloroplast kunye nokuziqhelanisa ngokukhawuleza notshintsho lwemo engqongileyo.
Ezinye iijene eziphambili ziye zahlala kwi-chloroplast genome ngenxa yokuba zifakela iiprotheyini ze-hydrophobic ezinzima ukungenisa, okanye ngenxa yokuba intetho yabo yendawo ivumela ukuphendula ngokukhawuleza ukuguquka kokukhanya kunye nezinye iimeko zangaphandle.
Ii-pigments kunye nemibala: i-chlorophyll kunye ne-accessory pigments
Chlorophyll a Yeyona pigment yokuqala enoxanduva lokufunxa ukukhanya kwelanga, ngakumbi kumaza abomvu naluhlaza okwesibhakabhaka, ebonisa uphawu lombala oluhlaza wezityalo. Kukwakho ne-accessory pigments eyenza banzi i-spectrum yokukhanya esetyenzisiweyo, njenge-chlorophyll b kunye no-c, kunye ne-carotenoids (i-carotenes kunye ne-xanthophylls).
Ukubaluleka kwezi pigments akukho kuphela kwiphotosynthesis, kodwa nakwimibala yamagqabi, iziqhamo kunye neentyatyambo. Kwi-algae, indibaniselwano yee-pigments imisela amandla azo okuphila kubunzulu obahlukeneyo, ithatha ithuba lokungenwa kwemibala ekhanyayo emanzini.
Iindidi ezahlukeneyo zeplastidi ziyakwazi ukugcina ii-pigments ezahlukeneyo. Ngokomzekelo, iichromoplasts zigcina ibala eliorenji, elibomvu nelityheli, ngoxa ii<em>leucoplasts zisebenza ngokukhethekileyo ekugcineni izinto ezingenambala ezifana nesitatshi neeoli.
Imvelaphi yendalo yekloroplasts kunye nokwahluka kweplastid
Imvelaphi yekloroplasts ichazwa yi ithiyori ye-endosymbioticIseli yakudala ye-eukaryotic ngempazamo yafaka i-photosynthetic cyanobacterium njenge-endosymbiont. Ngokuhamba kwexesha, i-cyanobacterium yaphulukana nokuzimela kwayo kwaye yadlulisela uninzi lwemizila yayo kwi-nucleus yomkhosi, ishiya iqhezu kuphela kwi-chloroplast genome. Ukususela ngoko, zonke iiplastids ezikhoyo-kwizityalo, i-algae, kunye nezinye i-photosynthetic eukaryotes-zithathwa njengenzala yeso siganeko sokuqala.
Imbali yendaleko yeplastids ikwabandakanya izehlo ze-endosymbiotic ezikwinqanaba lesibini kunye nenqanaba lesithathu, apho iiseli ze-eukaryotic ezingezizo iphotosynthetic zidityaniswe ne-algae epheleleyo kunye neechloroplasts esele zenziwe, ngaloo ndlela zibangela iyantlukwano yangoku, ngakumbi kwi-algae emdaka nebomvu kunye namanye amaqela aselwandle.
Ukulungelelanisa kunye nezinto ezinomdla: i-kleptoplasty kunye nobomi ngaphandle kwekloroplasts
Kukho izilwanyana, ezifana nenkumba yolwandle Elysia chlorotica, eziye zaphuhlisa ukukwazi ukugcina i-chloroplasts emva kokutya i-algae, ukuseka ubudlelwane bexeshana be-symbiotic obubizwa ngokuba ikleptoplastyEzi chloroplasts ezibiweyo (kleptoplasts) zinokuhlala zisebenza kwiinyanga kwaye zinike amandla kwisilwanyana nge-photosynthesis, into enomdla kakhulu kwi-biology ye-evolutionary and cellular.
Kwelinye icala, ezinye iiseli zezityalo, ezifana nezo ze-onion epidermis, azinazo iichloroplasts; bawaphuhlisa kuphela xa bevezwe ekukhanyeni, ukuqala kwi-precursor organelles ebizwa iiproplasts o ii-etioplastsIindidi ezahlukeneyo zeplastidi zibonisa amandla eseli yesityalo ukulungelelaniswa kunye nobuchule obukhethekileyo kwindawo yayo.
Uziqwalasela njani ii-chloroplasts phantsi kwe-microscope kunye neentlobo zeeseli ezicetyiswayo
I-Chloroplasts inokubonwa ngokulula kwiiseli zesityalo esitsha, ngakumbi kwi-mesophyll yeqabunga lemifuno efana ne-lettuce okanye isipinatshi, apho umbala wabo oluhlaza kunye nokuhamba kwe-intracellular kuququzelela ukuchongwa kwabo. Kuyenzeka ukujonga intshukumo yeechloroplasts kwi vivo, into eyaziwa ngokuba yi Intshukumo yeBrownian okanye i-cytoplasmic circulation, ilungele imifuniselo yesikolo neyebhubhoratri.
Ayizizo zonke iiseli zezityalo ezine-chloroplasts: ezo zikhethekileyo ekugcinweni okanye ekukhuselweni zihlala zingenazo, nangona zinokuphuhlisa ezinye iintlobo zeplastidi ngokuxhomekeke kwiimeko zokusingqongileyo kunye nemiqondiso yangaphakathi evela kwisityalo.
Imibuzo edla ngokubuzwa malunga neekloroplasts kwizityalo
- Ngaba ii-chloroplasts ziyadibana?
- Kwizityalo ezisemhlabeni, i-chloroplast fusion ayizange ibonwe, nangona iyenzeka kwezinye i-algae eluhlaza ngexesha le-sygamy (i-fusion yesondo).
- Iikloroplasts zisasazwa njani ngexesha lokwahlulwa kweeseli?
- Ukusasazwa kwenzeka ngendlela esebenzayo, edibene ne-actin filaments, ibeka i-chloroplasts ejikeleze i-nucleus ngaphambi kwe-mitosis ukuqinisekisa ukusabalalisa okulinganayo phakathi kweeseli zentombi.
- Ngaba zonke ii-chloroplasts zinenani elifanayo lemizila yemfuza?
- Inani lemizila yemfuza kwi-chloroplast DNA inokwahluka kancinci phakathi kweentlobo, kodwa ngokubanzi iba phakathi kwama-200 kunye nama-300, ikhowudi yemisebenzi ebalulekileyo efana nefotosynthesis, ukwakheka kweribosome, kunye nokuchazwa kofuzo.
- Ngaba ikloroplast ingadibanisa zonke iiproteni zayo?
- Hayi, uninzi lweeprotheyini ezisebenzayo zivela kwiijene ezibekwe kwinucleus yeseli kwaye zithunyelwa ngaphandle emva kokuba zenziwe kwi-cytosol.
