Isihloko: Isibonelo Semibuzo Yengxoxo Yokuphefumula Kwamaseli
I-Pendahuluan
Ukuphefumula kwamaseli kuyinqubo yamakhemikhali eyenzeka ngaphakathi kwamaseli ento ephilayo ukuze ikhiqize amandla ngesimo se-adenosine triphosphate (ATP). Le nqubo ibalulekile ekusindeni, njengoba i-ATP ingumthombo wamandla oyinhloko osetshenziselwa imisebenzi ehlukahlukene yamaseli. Ukuphefumula kwamaseli kuhilela uchungechunge oluyinkimbinkimbi lokusabela kwamakhemikhali nomoya-mpilo njengokwamukela ama-electron kokugcina, ngokuvamile kuhlukaniswe ngezigaba ezintathu eziyinhloko: i-glycolysis, umjikelezo we-Krebs, kanye nochungechunge lokuthuthwa kwama-electron. Lesi sihloko sizoxoxa ngezinkinga eziningana zezibonelo ezihlobene nokuphefumula kwamaseli futhi sinikeze izixazululo.
1. Imibuzo kanye nengxoxo mayelana ne-Glycolysis
Umbuzo: Chaza izigaba eziyinhloko enkambisweni ye-glycolysis kanye nomphumela wayo ekugcineni ekuphefumuleni kwamaseli.
Ingxoxo: I-Glycolysis iyisinyathelo sokuqala ekuphefumuleni kwamaseli futhi yenzeka ku-cytoplasm yamaseli. Yinqubo lapho i-molecule eyodwa ye-glucose (C₆H₁₂O₆) ihlukaniswa khona ibe ama-molecule amabili e-pyruvate (C₃H₄O₃). I-Glycolysis inezigaba ezimbili eziyinhloko: isigaba sokutshala amandla kanye nesigaba sokukhiqiza amandla.
– Isigaba Sokutshalwa Kwezimali Kwamandla: I-glucose iguqulwa ibe yi-fructose-1,6-bisphosphate ngokutshalwa kwe-ATP ezimbili.
– Isigaba Sokukhiqiza Amandla: I-Fructose-1,6-bisphosphate ihlukaniswa ibe ama-molecule amabili e-glyceraldehyde-3-phosphate abese eguqulwa abe yi-pyruvate, akhiqize i-ATP emine kanye ne-NADH ezimbili.
Sekukonke, i-glycolysis ikhiqiza ama-molecule amabili e-ATP (kukhiqizwa ama-ATP amane, kodwa ama-ATP amabili asetshenziswa kabusha) kanye nama-molecule amabili e-NADH nge-molecule ngayinye ye-glucose.
2. Imibuzo kanye nengxoxo mayelana nomjikelezo we-Krebs
Umbuzo: Yimuphi umkhiqizo okhiqizwa kusukela kumjikelezo we-Krebs we-molecule ngayinye ye-acetyl-CoA eyethulwayo?
Ingxoxo: Umjikelezo we-Krebs, owaziwa nangokuthi umjikelezo we-citric acid, wenzeka ku-mitochondria. I-molecule ngayinye ye-acetyl-CoA engena kulo mjikelezo idlula ochungechungeni lwezimpendulo ezikhiqiza:
– Ama-molecule amathathu e-NADH
– I-molecule eyodwa ye-FADH₂
– I-molecule eyodwa ye-GTP noma i-ATP
– Ama-molecule e-CO₂ amabili njengemikhiqizo yemfucuza.
Lo mjikelezo usebenza kabili nge-molecule ngayinye ye-glucose ehlukanisiwe, ngoba i-glycolysis ikhiqiza ama-molecule amabili e-pyruvate abese eguqulwa abe ama-molecule amabili e-acetyl-CoA.
3. Imibuzo kanye nengxoxo ngochungechunge lwezokuthutha lwe-electron
Umbuzo: Kungani umoya-mpilo ubalulekile eketangeni lokuthuthwa kwama-electron futhi uyini umkhiqizo wokugcina walolu chungechunge?
Ingxoxo: Uchungechunge lokuthuthwa kwama-electron lutholakala olwelwesini lwangaphakathi lwe-mitochondria futhi luqukethe uchungechunge lwezinhlanganisela zamaprotheni ezidlulisela ama-electron kusuka ku-NADH kanye ne-FADH₂ aye ku-oxygen ngochungechunge lwezimpendulo ze-redox.
I-oksijini iyona eyamukela ama-electron okugcina kule nqubo, yakha amanzi uma esabela nama-proton (H⁺). Ngaphandle kwe-oksijini, ama-electron awakwazi ukudlula ochungechungeni lokuthutha, amise ukukhiqizwa kwe-ATP futhi abangele ukunqwabelana kwe-NADH ne-FADH₂. Imikhiqizo yokugcina yochungechunge lokuthutha ama-electron yile:
– Amanzi (H₂O), akheka lapho ama-electron nama-proton ehlangana nomoya-mpilo.
– I-ATP eningi ikhiqizwa ngenqubo eyaziwa ngokuthi i-oxidative phosphorylation. Okungcono kakhulu, cishe i-ATP engu-34 ikhiqizwa nge-molecule ngayinye ye-glucose kulolu chungechunge.
4. Imibuzo kanye nezingxoxo ezihlobene nokusebenza kahle kwamandla
Umbuzo: Qhathanisa ukusebenza kahle kokuphefumula kwamaseli ngaphansi kwezimo ze-aerobic kanye ne-anaerobic.
Ingxoxo: Ukuphefumula nge-Aerobic kusebenza kahle kakhulu ekukhiqizeni i-ATP kunokuphefumula nge-anaerobic. Ngaphansi kwezimo ze-aerobic, i-molecule eyodwa ye-glucose ingakhiqiza kufika ku-38 ATP, kulandela ukulandelana okuphelele kwe-glycolysis, umjikelezo we-Krebs, kanye nochungechunge lokuthuthwa kwama-electron.
Ngokuphambene nalokho, ngaphansi kwezimo ze-anaerobic (ngaphandle komoya-mpilo), amaseli angadlula kuphela ku-glycolysis, ekhiqiza i-ATP engu-2 nge-molecule ye-glucose. Ukubiliswa, okuvame ukulandela i-glycolysis ngaphansi kwezimo ze-anaerobic, kuguqula i-pyruvate ibe yimikhiqizo efana ne-lactate noma i-ethanol kodwa akukhiqizi i-ATP eyengeziwe. Ukusebenza kahle kokuphefumula kwe-anaerobic kuphansi kakhulu ngoba inani le-ATP elikhiqizwayo lincane kakhulu.
5. Imibuzo kanye nengxoxo ngezinhlelo zokusebenza zokuphefumula kwamaselula
Umbuzo: Chaza ukuthi ukuphefumula kwamaseli kungathinteka kanjani ngokuba khona kobuthi obufana ne-cyanide.
Ingxoxo: I-Cyanide iwubuthi obuvimbela ukuphefumula kwamaseli ngokubopha ngokuqinile endaweni esebenzayo ye-enzyme i-cytochrome c oxidase (i-complex IV) ku-electron transport chain, okuvimbela ukudluliselwa kwama-electron ku-oxygen. Lokhu kubangela ukuvalwa okuphelele kwe-electron transport chain, okuvimbela i-ATP ukuthi ikhiqizwe ngempumelelo, okuholela ekuntulekeni kwamandla kwamaseli futhi mhlawumbe okuholela ekufeni kwamaseli. Lo mphumela ushesha kakhulu futhi uyabulala ngoba amaseli omzimba awatholi amandla adingekayo ukuze asinde.
Isiphetho
Ukuphefumula kwamaseli kuyinqubo ebalulekile evumela izinto eziphilayo ukuthi zisebenzise amandla agcinwe kuma-molecule ezinto eziphilayo. Ukuqonda izigaba zokuphefumula kwamaseli, imikhiqizo ekhiqizwayo, kanye nezici ezingathonya le nqubo kuyisisekelo esibalulekile ku-biology. Ngokutadisha lezi zinkinga nezingxoxo zezibonelo, singakha ukuqonda okungcono kokuthi imizimba yethu ikhiqiza futhi iphathe kanjani amandla ngesikhathi somsebenzi wamaseli. Le nqubo eyinkimbinkimbi ayigcini nje ngokunquma ukusebenza kahle kwamandla komzimba kodwa futhi idlala indima ekulinganiseni kwe-metabolic kanye nokuzivumelanisa kwayo nezimo zemvelo ezahlukahlukene.
