Impela kudingeke ukuthi ufunde ku-biology esinye sezigaba zomzimba zokuphefumula kwamaselula okwenzeka emzimbeni wethu. Imayelana ne- Umjikelezo weKrebs. Kuyaziwa nangegama lomjikelezo we-citric acid futhi kuyisigaba semethabolic esenzeka kumatrix we-mitochondrial wamaseli ezilwane.
Kulesi sihloko sizokutshela ukuthi yiziphi izici futhi sizochaza igxathu negxathu ukuthi yini umjikelezo wamaKrebs nokubaluleka kwawo.
Ukuphefumula kwamaselula
Ngaphambi kokuqala ukuchaza ukuthi yini umjikelezo weKrebs, kufanele sikhumbule ukuthi ukuphefumula kwamaselula kuqukethe izigaba ezintathu. Ake sibone ukuthi yisiphi isigaba ngasinye:
- I-Glycolysis: Le yinqubo lapho i-glucose yehlukaniswa yaba izingxenye ezincane. Phakathi nale nqubo kwakhiwa i-pyruvate noma i-pyruvic acid ezoholela ku-Acetyl-CoA.
- Umjikelezo weKrebs: Kumjikelezo weKrebs, i-Acetyl-CoA ixhunywe ku-CO2.
- Uchungechunge lokuphefumula: lapha amandla amaningi akhiqizwa ngokudluliswa kwama-electron avela ku-hydrogen. La mandla avela ekususweni kwezinto ezibandakanyekayo kuzo zonke izinyathelo zangaphambilini.
Uyini umjikelezo wamaKrebs
Siyazi ukuthi kungumjikelezo oyinkimbinkimbi nokuthi unemisebenzi eminingi esiza ukwakheka kweseli. Ngaphandle kwalo mjikelezo, amaseli abengekho noma angafeza imisebenzi ebalulekile. Umgomo oyinhloko womjikelezo wamaKrebs ukukhuthaza ukuwohloka kwemikhiqizo yokugcina yemetabolism yama-carbohydrate, lipids namanye ama-amino acid. Zonke lezi zinto ezifakwe emzimbeni ngokudla ziguqulwa zibe yi-Acetyl-CoA ngokukhishwa kwe-CO2 ne-H2O kanye nokuhlanganiswa kwe-ATP.
Yilapho kukhiqizwa khona amandla okufanele asetshenziswe amaseli ukwenza imisebenzi yawo. Phakathi kwezigaba ezahlukahlukene zomjikelezo we-citric acid sithola izixhumanisi ezahlukahlukene ezisetshenziswa njengezandulela ku-biosynthesis yama-amino acid namanye ama-biomolecule. Ngomjikelezo weKrebs sithola amandla avela kuma-molecule okudla okuphilayo futhi zidluliselwa kuma-molecule zihlala ukuthekelisa amandla okusetshenziswa emisebenzini yeselula. Ngalo mandla singenza imisebenzi yethu ebalulekile nemisebenzi yomzimba yosuku lwethu usuku nosuku.
Emjikelezweni weKrebs kunokunye okwenzeka ikakhulukazi emakhemikhali e-oxidative. Konke lokhu kusabela kudinga umoya-mpilo ukwenzeka. Ukuphendula ngakunye kwamakhemikhali kunokubamba iqhaza kwamanye ama-enzyme atholakala kwi-mitochondria. La ma-enzyme anesibopho sokuvuselela ukusabela. Uma sikhuluma ngokuvuselela ukusabela sikhuluma ngokwandisa ijubane laso. Kunezinto eziningi ezihehayo ezisiza ukusabela kwamakhemikhali kwenzeke ngokushesha kunokujwayelekile.
Izinyathelo zomjikelezo weKrebs
Njengoba sishilo phambilini, kulo mjikelezo kunezinto ezahlukahlukene ezenzeka ngamakhemikhali ezidinga umoya-mpilo. Ukusabela kokuqala kwakho konke yi-oxidative decarboxylation ye-pyruvate. Kulokhu kusabela, i-glucose etholakala ekonakaleni kwama-hydrate anempandla iguqulwa ibe ngama-molecule amabili we-pyruvic acid noma i-pyruvate. Iglucose yehliswa ngeGlycolysis futhi iba ngumthombo obalulekile we-Acetyl-CoA. I-decarboxylation ye-oxidative ye-pyruvate iqala ngomjikelezo we-citric acid. Lokhu kusabela kwamakhemikhali kufana nokuqedwa kwe-carbon dioxide ne-pyruvate ekhiqizwa eqenjini le-acetyl elibophezela ku-coenzyme A. Kule mpendulo yamakhemikhali, i-NADH ikhiqizwa njengemolekyuli ethwala amandla.
Ngokwakheka kwe-Acetyl-CoA molecule, umjikelezo weKrebs uqala kumatrix we-mitochondria. Inhloso ukuhlanganisa uchungechunge lwe-oxidation yeselula ukwenza i-carbons i-oxidize bese uyiguqula ibe yi-carbon dioxide. Kukho konke lokhu kuphendula kwamakhemikhali udinga ubukhona be-oxygen. Ngakho-ke, inqubo yokuphefumula kwamaselula ibaluleke kakhulu.
Umjikelezo we-Krebs uqala nge-enzyme citrate synthetase esebenza ukukhuthaza ukusabela kwamakhemikhali kokudluliswa kweqembu le-Acetyl kuya ku-oxaloacetic acid eyakha i-citric acid kanye nokukhishwa kwe-coenzyme A. Igama lomjikelezo lihlobene nokwakheka kwe-asidi ezisawolintshi nakho konke ukusabela kwamakhemikhali okwenzeka lapha.
Ukuqhubeka kokuxhuma kanye nokusabela kwe-decarboxylation kwenzeka kulezi zinyathelo ezilandelayo. Lokhu kusabela kudala i-ketoglutaric acid. Ngesikhathi kwenziwa le nqubo, kukhishwa i-carbon dioxide bese kwakhiwa i-NADH ne-H. Le ketoglutaric acid ibhekana ne-oxidative decarboxylation reaction ehlanganiswa nenkinga ye-enzyme lapho i-Acetyl CoA ne-NAD beyingxenye yayo. Konke lokhu kuphendula kuzoholela ku-succinic acid, i-NADH, kanye ne-molecule ye-GTP okwalandela lokho izodlulisela amandla ayo kwi-molecule ye-ADP ekhiqiza i-ATP.
Kusukela nje ezinyathelweni zokugcina sizobona ukuthi i-acid ye-succinic izokhiqiza i-fumaric acid eyaziwa nangokuthi i-fumarate. I-coenzyme yayo yi-ADF. Lapha kuzokwakhiwa i-FADH2, engenye ye-molecule ethwala amandla. Ekugcineni, i-fumaric acid ayimnandi ukukwazi ukwakha i-malic acid eyaziwa nangokuthi i-malate. Ekugcineni emjikelezweni weKrebs, i-malic acid izofakwa i-oxidized ukuze yakhe i-oxaloacetic acid, bawuqale kabusha umjikelezo. Futhi konke ukusabela kuzokwenzeka ngasikhathi sinye bese kuqala futhi.
Ukubaluleka
Kunezigidi zezimpikiswano zokwazi ukuthi umjikelezo weKrebs ubaluleke kakhulu ekwakheni isisindo semisipha nokusebenza kahle komzimba. Ukuze lo mjikelezo usebenze kahle kunezakhi zomzimba ezi-5 eziyisisekelo umzimba wethu okudingeka uzenze: i-thiamine, i-riboflavin, i-niacin, i-iron ne-glutamine. Lawa ngama-amino acid asetshenziselwa ukwakheka kwezicubu ezintsha zemisipha. Ngakho-ke, kuyadingeka ukwazi ukuthi lo mjikelezo usebenza kanjani ukugcizelela ukondleka okuhle ukuze wandise ukusebenza nobukhulu bemisipha.
Kuyasiza futhi ukwazi umjikelezo wamaKrebs ukugwema izifo eziningi ngenxa yamandla noma ukushiyeka kwezakhi emzimbeni wethu. Njengoba ukwazi ukubona, konke lokhu kuphendula kwamakhemikhali kwenzeka ngasikhathi sinye emzimbeni ukuqinisekisa ukusebenza kahle.
Ngiyethemba ukuthi ngalolu lwazi ungafunda kabanzi ngomjikelezo weKrebs nokubaluleka kwawo.