Krebs Cycle: Lub Citric Acid Cycle hauv Kev Siv Hluav Taws Xob
Lub voj voog Krebs, tseem hu ua lub voj voog citric acid, yog ib qho kev tshuaj lom neeg uas ua lub luag haujlwm tseem ceeb hauv kev ua haujlwm ntawm lub cev. Lub npe no tau muab los ntawm Hans Krebs, tus kws tshawb fawb German-British uas tau tshawb pom nws hauv xyoo 1937, nws yog lub hauv paus ntawm kev ua haujlwm ntawm lub zog hauv cov kab mob aerobic. Hauv tsab xov xwm no, peb yuav kawm tob dua txog lub tshuab, lub luag haujlwm, thiab qhov tseem ceeb ntawm lub voj voog no hauv kev tshawb fawb niaj hnub no.
Kev Taw Qhia rau Lub Voj Voog Krebs
Lub voj voog Krebs tshwm sim hauv mitochondria, "lub zog" ntawm lub cell, uas yog qhov chaw tseem ceeb rau kev tsim cov adenosine triphosphate (ATP), lub zog nqa lub cellular. ATP yog tsim los ntawm oxidative phosphorylation, thiab lub voj voog Krebs ua haujlwm ua ib kauj ruam tseem ceeb hauv cov txheej txheem no. Lub voj voog no yog ib feem ntawm txoj kev loj dua uas suav nrog glycolysis thiab cov saw hlau thauj hluav taws xob.
Ua ntej nkag mus rau hauv lub voj voog Krebs, cov pyruvic acid molecule, ib yam khoom ntawm glycolysis, raug hloov mus ua acetyl coenzyme A (acetyl-CoA). Cov txheej txheem no tso tawm ib lub molecule ntawm carbon dioxide thiab tsim NADH los ntawm NAD+, uas tom qab ntawd siv rau hauv cov saw hlau thauj hluav taws xob los tsim ATP.
Cov Theem Krebs Cycle
Lub voj voog citric acid muaj yim kauj ruam tseem ceeb, txhua kauj ruam yog catalyzed los ntawm ib qho enzyme tshwj xeeb. Cov kauj ruam no yog raws li nram no:
1. Kev Tsim Citrate: Acetyl-CoA muab nws pawg acetyl nrog rau plaub-carbon oxaloacetate molecule, tsim rau-carbon citrate, los ntawm kev ua haujlwm ntawm cov enzyme citrate synthase.
2. Isomerization ntawm Citrate rau Isocitrate: Los ntawm cov enzyme aconitase, citrate dhau los ntawm isomerization rau isocitrate los ntawm kev tsim cov molecule cisocitrate nruab nrab.
3. Oxidative Decarboxylation ntawm Isocitrate: Isocitrate yog oxidized los ntawm enzyme isocitrate dehydrogenase, hloov nws mus rau alpha-ketoglutarate, thaum tso tawm carbon dioxide thiab hloov NAD + mus rau NADH.
4. Kev Tsim Succinyl-CoA: Alpha-ketoglutarate raug oxidative decarboxylation los ntawm enzyme alpha-ketoglutarate dehydrogenase, tsim succinyl-CoA thiab tso tawm cov pa roj carbon dioxide thib ob, nrog rau kev tsim NADH.
5. Kev Tsim Succinate: Los ntawm kev tshuaj tiv thaiv catalyzed los ntawm succinyl-CoA synthetase, succinyl-CoA hloov pauv mus ua succinate, uas kuj tsim ib lub molecule ntawm guanosine triphosphate (GTP), uas tuaj yeem hloov pauv mus ua ATP tau yooj yim.
6. Kev Oxidation ntawm Succinate mus rau Fumarate: Cov enzyme succinate dehydrogenase catalyzes qhov oxidation ntawm succinate mus rau fumarate. Qhov kev tshuaj tiv thaiv no kuj tsim FADH2 los ntawm FAD, uas tom qab ntawd siv rau hauv cov saw hlau thauj hluav taws xob.
7. Kev Ua Kom Fumarate Muaj Dej Rau Malate: Cov enzyme fumarase ua rau muaj kev ntxiv dej rau hauv fumarate, ua rau malate.
8. Kev Oxidation ntawm Malate mus rau Oxaloacetate: Kauj ruam kawg yog catalyzed los ntawm malate dehydrogenase, uas oxidizes malate rov qab mus rau oxaloacetate, tsim cov NADH kawg los ntawm NAD +.
Nrog rau kev tsim dua ntawm oxaloacetate, lub voj voog npaj txhij pib dua nrog cov acetyl-CoA molecules tshiab.
Lub Luag Haujlwm ntawm Krebs Cycle hauv Cellular Energy
Txhua zaus ntawm lub voj voog Krebs, ib qho acetyl-CoA raug hloov pauv tag nrho, tsim ob lub molecule carbon dioxide, peb lub molecule NADH, ib lub molecule FADH2, thiab ib lub GTP/ATP. Tom qab ntawd NADH thiab FADH2 raug pub rau hauv cov saw hlau thauj hluav taws xob, qhov twg lub zog khaws cia siv los tsim cov proton gradient uas ua rau ATP synthesis. Yog li, thaum lub voj voog Krebs tsis tsim ntau ATP ncaj qha, nws qhov kev koom tes tseem ceeb yog nyob rau hauv kev tsim cov khoom sib npaug uas tsav oxidative phosphorylation.
Lub Ntsiab Lus Tseem Ceeb ntawm Lub Voj Voog Krebs
Lub voj voog Krebs yog lub hauv paus ntawm kev hloov pauv zog ntawm lub cev, ua rau cov hlwb siv lub zog los ntawm ntau yam khoom noj khoom haus. Cov amino acids, cov fatty acids, thiab cov carbohydrates tuaj yeem tawg ua cov molecules uas tuaj yeem nkag mus rau hauv lub voj voog no. Raws li qhov chaw sib sau ua ke tseem ceeb hauv kev hloov pauv, lub voj voog citric acid muab txoj hauv kev tseem ceeb rau kev sib txuas thiab kev tswj hwm ntawm ntau txoj hauv kev hloov pauv.
Tsis tas li ntawd xwb, cov khoom seem ntawm lub voj voog no kuj siv rau hauv biosynthesis ntawm cov roj fatty acids, amino acids, thiab lwm yam khoom siv hauv lub cev, qhia txog nws qhov kev hloov pauv thiab lub luag haujlwm tseem ceeb hauv cellular homeostasis.
Kev Tswj Xyuas Lub Voj Voog Krebs
Kev ua haujlwm ntawm lub voj voog Krebs raug tswj los ntawm kev xav tau lub zog ntawm tes thiab kev muaj cov khoom siv hauv paus. Qee cov txheej txheem tswj hwm suav nrog:
- Kev Tiv Thaiv Kev Tawm Tswv Yim: Cov tshuaj molecules xws li ATP, NADH, thiab lawv cov khoom kawg tuaj yeem tiv thaiv kev ua haujlwm ntawm cov enzymes hauv lub voj voog, txo qhov nrawm ntawm cov txheej txheem thaum lub zog txaus.
– Cov tshuaj ua kom lub cev ua haujlwm tau zoo: ADP lossis AMP, uas qhia txog qhov xav tau lub zog ntawm lub cell, tuaj yeem ua kom cov enzymes ua haujlwm tau zoo kom lub voj voog ua haujlwm sai dua.
– Kev Muaj Khoom Siv: Qhov ntau ntawm oxaloacetate lossis acetyl-CoA tuaj yeem cuam tshuam rau qhov nrawm ntawm lub voj voog.
Kev Cuam Tshuam Txog Kev Kho Mob thiab Kev Tshawb Fawb
Kev ua haujlwm tsis zoo hauv lub voj voog Krebs tuaj yeem ua rau muaj ntau yam kab mob, suav nrog mob qog noj ntshav, ntshav qab zib, thiab kev puas tsuaj ntawm lub paj hlwb. Piv txwv li, qee cov hlwb qog noj ntshav qhia txog kev hloov pauv hauv lub voj voog no los txhawb kev loj hlob tsis tuaj yeem tswj tau, thiab yog li ntawd, cov khoom ntawm lub voj voog Krebs feem ntau yog tsom rau kev tsim cov kev kho mob qog noj ntshav.
Kev tshawb fawb txuas ntxiv mus nkag siab zoo dua txog kev tswj hwm ntawm lub voj voog no thiab nws txoj kev sib raug zoo rau tib neeg kab mob. Kev nkag siab tob dua tuaj yeem ua rau muaj kev tshawb pom tshiab hauv kev kuaj mob, kev kho mob, thiab kev tiv thaiv ntau yam mob.
Xaus
Lub voj voog Krebs yog lub hauv paus ntawm kev hloov pauv zog ntawm lub cev. Nws txuas thiab hloov ntau lwm txoj hauv kev hloov pauv, txhawb nqa ATP tsim thiab biosynthesis ntawm cov khoom tseem ceeb ntawm lub cev. Raws li ib qho tseem ceeb ntawm kev hloov pauv, kev nkag siab zoo txog lub voj voog citric acid muaj cov txiaj ntsig dav dav xws li kev tshawb fawb yooj yim mus rau kev siv hauv kev kho mob. Los ntawm kev tshawb nrhiav txuas ntxiv, lub voj voog no yuav tseem yog thaj chaw tseem ceeb ntawm kev kawm hauv biochemistry thiab tshuaj.
