Isigaba esimnyama se-photosynthesis

I-oksijeni iyona nxalenye ebalulekileyo ebakho bonke ubomi emhlabeni. Okumangalisa kukuba, eli nqaku kwiplanethi yethu, nangona ukugxininiswa kwimoya ngokwezinye izazinzulu ngokunciphisa ukungaphumeleli, kuyisisitye sokugcina. Ukubetha ngakumbi kukuba lihlanganiswa ukusuka kwizinto ezinokuba zikhona - amanzi, ilanga kunye necarbon dioxide. Kwaye baqhuba le nkqubo emangalisayo yesityalo.

Ewe, sithetha nge-photosynthesis - indalo emangalisayo yendalo. Nangona inzululwazi ifundele ngolu hlobo, akunakwenzeka ukuphinda izigaba ze-photosynthesis kwi-laboratory kuze kube namhlanje.

Le nkqubo ivame ukuhlukana zibe zigaba ezimbini:

• Isigaba sokukhanya se-photosynthesis.
• Isigaba esimnyama se-photosynthesis.

Ukusuka egameni labo kuyacaca ukuba inxalenye yokuqala yenkqubo iqhubeka ekukhanyeni, oko kukuthi, ngokuthatha inxaxheba kwelanga. Lwenzeka kuphela kumaqabunga aluhlaza kwizityalo, kuba ziqukethe i-chloroplasts - izinto ezikhethekileyo, kwiimbumba apho ukuhlanganiswa kwe-ATP - i-molecule apho kugcinwa khona amandla.

Xa i-sun photons ishaya amaqabunga ezityalo eziqukethe i-chlorophyll, amandla okukhanya kwelanga aguqulwa abe yi-molecule yamandla ye-ATP, esele ikhankanywe ngasentla. Ukongezelela, ngenxa yokuqhekeka kwee-athomu ezimbini ze-hydrogen ezivela kwi-molecule yamanzi (eyenzekayo ngoncedo lwelanga), i-molecule ye-NADP yenziwa. Ilamleksi yamanzi edibeneyo, engenamathomo amabini e-hydrogen, ihlala i-oksijeni yamahhala, engena emoyeni. Ngaloo ndlela, iimveliso ze-photosynthesis kwisigaba sokukhanya zi:

• Oxygen;
• Imolekyuli yamandla ye-ATP;
• I-atomic hydrogen i-NADP H2.

Kunomdla ukuba ukubunjwa kwe-oksijini kule nkqubo akusiyo yonke injongo. Kunoko, yiphumo elisecaleni. Emva koko kukho isigaba esimnyama se-photosynthesis, okanye i-chemosynthesis, apho iimveliso zesigaba sokuqala zibandakanyeke ngqo. Makhe siqwalasele ngokubanzi.

Enyanisweni, injongo yenkqubo ayiyiyo ukwakheka kwe-oksijini. Isigaba esimnyama se-photosynthesis senza kwenye indawo yeqabunga-kwi-stroma ye-chloroplasts yayo. Ekupheleni kwesigaba sokukhanya, isityalo sisebenzela ukugcina inani elimangalisayo lamamolekyuli wamandla - i-ATP kunye ne-NADP H2, ngoko ke ukuthatha inxaxheba kokukhanya akusekho mfuneko. Kukuncediswa kwezi iimlekyuli ukuhlanganiswa kwezinto eziphilayo. Kunengqiqo ukuba umsebenzi we-molecule yamandla ye-ATP kukunikezelwa kwamandla kwiinkqubo zokuqala, ngelixa indima ye-NADPH kukunciphisa.

Ekuqaleni kwesi sigaba i-molecule eyanciphayo idibeneyo, ngenxa yokuba i-atom e-hydrogen ezimbini iphela, ebonisa i-molecule ye-NADPH ecocekileyo kwimveliso. Ngexesha elifanayo, i-ATP inika lonke i-phosphoric acid, ijika kwi-ADP. Ezi zimbini iinkqubo zenzeka kwi-matrix yephepha. Ama-molecule esandula athola abuyele emacaleni amaqabunga, okwenza kube lula ukuphinda yonke inkqubo yesigaba sokukhanya. Nangona kunjalo, oku akuyona inkqubo ephambili ye-photosynthesis, sivele sibonise ukuhamba kunye nokulandelelana kwemisebenzi eyenzeka kumaqabunga.

Imveliso yokugqibela kwesi sigaba yi-glucose, i-organic component eyenziwa kwiishukela ezilula. UMelvin Calvin wayengowokuqala ukuchaza ukuhlanganiswa kwale molekyu ngokubanzi. Kwafunyaniswa ukuba zombini iamolekyu, eziqwalaselwe kwisiseko sesigaba sokukhanya, amandla kunye nokunciphisa, kuthatha inxaxheba kwiinkqubo zokuqala. Ukongezelela, ii-molecule ze-carbon dioxide (CO2), ii-athomu zama-hydrogen ezingama-24, iamolekyu zamanzi ezi-6 zibaluleke kakhulu ekubunzeni iishukela ezilula:

6CO2 + 24H + ATP C6H12O6 + 6H2O.

Isigaba esimnyama se-photosynthesis kubalulekile kwizityalo kuba ngaphezu kwe-glucose ngeli xesha, i-amino acid, i-nucleotide, i-acids e-fatty kunye ne-glycerol zenziwa.

I-Photosynthesis yinkqubo yendalo ekhethekileyo. Akusiyo nje isibambiso sokugcina isilinganiselo esiphezulu somoya omoya kunye nocingo lwe-ozone, kodwa kwakhona ukuphelela kwendalo xa izinto zendalo zidalwe kwizinto ezingenakwenzeka.