Indima yeMitochondria ekukhiqizweni kwamandla eselula
Ama-Mitochondria avame ukubizwa ngokuthi "izindawo zamandla" zamaseli, futhi indima yawo ekukhiqizweni kwamandla ayinakweqiswa. Lezi zakhiwo ziyizingxenye ezibalulekile zamaseli e-eukaryotic, okuqinisekisa ukuthi izinto eziphilayo zinokunikezwa kwamandla okwanele kwemisebenzi eyahlukahlukene yezinto eziphilayo. Lesi sihloko sizohlola ngokujulile ukuthi i-mitochondria inikela kanjani ekukhiqizweni kwamandla eseli, izindlela ezihilelekile, kanye nokubaluleka kwazo empilweni yamaseli kanye neyonke yezinto eziphilayo.
Isingeniso: Ayini amaMitochondria?
Ama-Mitochondria angama-organelle anezindonga ezimbili atholakala cishe kuwo wonke amaseli e-eukaryotic. Abizwa nangokuthi "izindawo zamandla" zeseli, i-mitochondria yizikhungo eziyinhloko zokukhiqizwa kwe-adenosine triphosphate (ATP), i-molecule yamandla eyinhloko esetshenziswa amaseli ezinqubweni ezahlukahlukene ze-metabolic. Lezi zakhiwo zinezimbotshana ezimbili: ulwelwesi lwangaphandle olubushelelezi kanye nolwelwesi lwangaphakathi olunemifantu, okwakha izakhiwo ezibizwa ngokuthi i-cristae. Ama-cristae adlala indima ebalulekile ekwandiseni indawo engaphezulu yolwelwesi lwangaphakathi, olubalulekile ekukhiqizweni kwe-ATP.
Ukukhiqizwa kwe-ATP eMitochondria
Ukukhiqizwa kwe-ATP ku-mitochondria kwenzeka ngenqubo eyaziwa ngokuthi i-oxidative phosphorylation, isigaba sokugcina sokuphefumula kwamaseli. Ukuphefumula kwamaseli uchungechunge lwezimpendulo zamakhemikhali ezihilela ukuguqulwa kwamandla avela ekudleni abe yi-ATP. Ukuphefumula kwamaseli kunezigaba ezintathu eziyinhloko: i-glycolysis, umjikelezo we-citric acid (umjikelezo we-Krebs), kanye ne-oxidative phosphorylation.
1. I-Glycolysis yisigaba sokuqala sokuphefumula kwamaseli futhi senzeka ku-cytoplasm. Kulesi sigaba, i-glucose ihlukaniswa ibe ama-molecule amabili e-pyruvate, okukhiqiza inani elincane le-ATP kanye ne-NADH (i-nicotinamide adenine dinucleotide).
2. Umjikelezo we-Citric Acid wenzeka ku-mitochondrial matrix. I-pyruvate ekhiqizwa yi-glycolysis iguqulwa ibe yi-acetyl-CoA, bese ingena emjikelezweni we-citric acid. Kulo mjikelezo, i-acetyl-CoA ihlukaniswa ibe yi-carbon dioxide, bese amandla avelayo adluliselwa kuma-molecule e-electron carrier NADH kanye ne-FADH2 (flavin adenine dinucleotide).
3. I-oxidative phosphorylation yenzeka kulwelwesi lwangaphakathi lwe-mitochondrial. I-NADH ne-FADH2, ezikhiqizwa umjikelezo we-citric acid, zikhipha ama-electron ngochungechunge lokuthuthwa kwama-electron. Lokhu kudluliswa kwama-electron kudala i-proton gradient kulo lonke ulwelwesi lwangaphakathi lwe-mitochondrial, olukhuthaza ukukhiqizwa kwe-ATP nge-enzyme i-ATP synthase.
Uchungechunge lokuthuthwa kwama-electron luqukethe uchungechunge lwezinhlanganisela zamaphrotheni ezifakwe kulwelwesi lwangaphakathi lwe-mitochondrial. Ama-electron avela ku-NADH kanye ne-FADH2 adluliselwa ngalezi zinhlanganisela, futhi amandla akhishwe asetshenziselwa ukupompa ama-proton avela ku-mitochondrial matrix aye esikhaleni se-intermembrane, okudala i-proton gradient. I-ATP synthase, enye i-protein complex, ivumela ama-proton ukuthi abuyele ku-mitochondrial matrix, futhi amandla avela ku-proton gradient asetshenziselwa ukuhlanganisa i-ADP kanye ne-inorganic phosphate ukuze kwakheke i-ATP. Kule nqubo, i-oxygen isebenza njengomamukeli wokugcina wama-electron futhi ihlangana nama-proton ukuze kwakheke amanzi.
Indima yeMitochondria kuMetabolism yamaSeli
Ngaphezu kokukhiqizwa kwe-ATP, ama-mitochondria nawo ahilelekile kwezinye izici ezahlukahlukene ze-metabolism yamaseli, njengokukhiqizwa kwama-metabolites aphakathi adingekayo ekwakhiweni kwama-amino acid, ama-lipid, nama-nucleotide. I-Mitochondria isebenza futhi ku-calcium ion homeostasis, ebalulekile emisebenzini ehlukahlukene yamaseli, okuhlanganisa ukufinyela kwemisipha kanye nokulawulwa kwe-metabolism yamandla.
Lokhu kulinganisela okuphelele komsebenzi we-mitochondrial kudala ibhalansi esekela impilo yamaseli. Ama-metabolites amaningi akhiqizwa emjikelezweni we-Krebs ahilelekile kwezinye izindlela zokwenziwa kwezinto eziphilayo. Isibonelo, i-citrate ephuma kwi-mitochondria ingasetshenziswa kwi-cytoplasm ukuze kuhlanganiswe ama-fatty acid.
I-Mitochondria kanye ne-Apoptosis
Ngaphezu kwendima yazo ekukhiqizweni kwamandla kanye nokusetshenziswa kwe-metabolism, i-mitochondria nayo iyizikhungo ezibalulekile zokulawula i-apoptosis, noma ukufa kwamaseli okuhleliwe. I-apoptosis iyindlela ebalulekile esetshenziswa yizinto eziphilayo ukuqeda amaseli alimele noma angadingekile futhi idlala indima ebalulekile ekukhuleni nasekulawuleni ikhwalithi yezicubu.
I-Mitochondria ingakhipha izinto ezibangela ukuvuvukala njenge-cytochrome c kuyi-cytoplasm ngenxa yokucindezeleka noma umonakalo weseli. Lezi zinto zibe sezibangela uchungechunge lwezenzo eziholela ekusebenzeni kwama-enzyme e-protease abizwa ngokuthi ama-caspases, okuholela ekugcineni ekuwohlokeni kwezingxenye zeseli nokufa kweseli.
Umphumela Wezinkinga Ze-Mitochondrial Empilweni
Ukungasebenzi kahle kwe-mitochondrial kungaba nomthelela ezifweni ezahlukahlukene, okuhlanganisa izifo eziwohlokayo, ezithinta umzimba, kanye nezenhliziyo. Isibonelo, isifo sikaParkinson kanye ne-Alzheimer's sihlotshaniswa nomonakalo we-mitochondrial oholela ekukhiqizweni okukhulu kwama-free radical, okulimaza izingxenye ezibalulekile zamaseli. Ngokufanayo, isifo sikashukela sohlobo 2 kanye nesifo senhliziyo kuvame ukubandakanya ukuphazamiseka ekukhiqizweni kwamandla e-mitochondrial kanye ne-homeostasis engasebenzi kahle ye-metabolic.
Ukuguquka kwezakhi zofuzo ku-DNA ye-mitochondrial kungathinta nokusebenza kwe-mitochondrial. I-DNA ye-mitochondrial, ezuzwe kumama, ifaka izingxenye eziningana ezibalulekile zeketanga lokuthuthwa kwama-electron. Ukuguquka kwezakhi zofuzo kungabangela izifo ze-mitochondrial njenge-MELAS syndrome (i-myopathy, i-encephalopathy, i-lactic acidosis, kanye neziqephu ezifana ne-stroke) kanye ne-Leigh syndrome.
Isiphetho
Indima ye-mitochondria ekukhiqizweni kwamandla eseli iyisisekelo. Njengesikhungo esiyinhloko sokukhiqizwa kwe-ATP ngokuphefumula kwamaseli, i-mitochondria isekela cishe zonke izici zomsebenzi wamaseli kanye nokuphila komzimba. Ngaphezu kokukhiqizwa kwamandla, i-mitochondria idlala indima ekusetshenzisweni kwe-metabolism, ukulawulwa kwama-ion, kanye ne-apoptosis. Ukungahambi kahle komsebenzi we-mitochondrial kungaholela ezimweni ezahlukahlukene ze-pathological. Ngakho-ke, ukuqonda umsebenzi we-mitochondrial nokugcina i-mitochondria enempilo kubalulekile enhlalakahleni iyonke yomzimba.
Ngokuqonda kangcono indlela esebenza ngayo i-mitochondria, singakha amasu angcono okwelapha nokuvimbela izifo ezibangelwa ukungasebenzi kahle kwe-mitochondrial. Ngocwaningo oluqhubekayo, ithemba lethu ukusebenzisa amandla aphelele ala "mandla" eseli ukuthuthukisa impilo kanye nekhwalithi yokuphila.
