Nokuba uyifundile ibhayoloji kwisikolo samabanga aphakamileyo, okanye ufunda malunga nokuzuza kobunzima bemisipha, ngokuqinisekileyo uvile nge Umjikelo weKrebs. Elinye lamanqanaba emetabolism yokuphefumla kwamaselula okwenzeka emzimbeni wethu. Kwakhona kwaziwa ngegama lomjikelezo we-citric acid kunye nesigaba se-metabolic esenzeka kwimatriki ye-mitochondrial yazo zonke iiseli zezilwanyana.
Kule nqaku siza kukuxelela ukuba zeziphi iimpawu, inyathelo nenyathelo ngamalungu omjikelo we-krebs kunye nokubaluleka kwawo kwinqanaba ngokubanzi.
Amanqanaba okuphefumla kweselula
Ngaphambi kokuba sichaze ukuba yintoni umjikelo we-kreb, kufuneka sikhumbule ukuba kusebenza njani ukuphefumla kweselula, kuba kubaluleke kakhulu. Makhe sibone ukuba zeziphi izigaba zokuphefumla kweselula. Kwenzeka kwizigaba ezi-3 eziphambili:
- IGlycolysis: yinkqubo apho iswekile yahlulwe yangamacandelo amancinci. Ngexesha lale nkqubo kwenziwa i-pyruvate okanye i-pyruvic acid eya kuthi ikhokelele kwi-Acetyl-CoA.
- Umjikelo weKrebs: Kumjikelo we-Krebs, i-Acetyl-CoA ixutywe kwi-CO2.
- Ikhonkco lokuphefumula: Uninzi lwamandla luveliswa apha ngokudluliselwa kwee-elektroni kwihydrogen. La mandla avela ekuphelisweni kwezinto ezithatha inxaxheba kuwo onke amanyathelo angaphambili.
Uthini umjikelo we krebs
Usebenza njani ukuphefumla kwamaselula, okubandakanyiweyo kwelinye lamanyathelo alo mjikelo, masibone ukuba ungantoni na. Siyazi ukuba ngumjikelo ontsonkothileyo kwaye unemisebenzi emininzi encedisa imetabolism yeselula. Ngaphandle kwalo mjikelo, zonke iiseli azinakho ukwenza imisebenzi ebalulekileyo emzimbeni wethu. Eyona njongo iphambili yomjikelo we-krebs kukukwazi ukukhuthaza ukonakala kweemveliso zokugqibela zemetabolism yee-carbohydrate, lipids kunye nezinye iiamino acid.
Xa sisitya ukutya kufuneka sazi ukuba ezona macronutrients ziicarbohydrate, iiproteni kunye namafutha. Iiproteni, nazo, zenziwe ngama-amino acid. Ngesi sizathu, kwinkqubo yokondla umjikelo we krebs ubaluleke kakhulu. Zonke izinto ezifakwe emzimbeni ngokutya ziba kwi-Acetyl-CoA ngokukhutshwa kwe-CO2 kunye ne-H2O kunye nokudityaniswa kwe-ATP.
Ndiyabulela kolu luhlu, kulapho amandla eeseli kufuneka awasebenzise ukwenza imisebenzi yawo. Sinabalamli abahlukeneyo kuwo onke amabakala omjikelo abawasebenzisayo njengabandulelayo xa kudityaniswa ii-amino acid kunye nezinye i-biomolecule. Enkosi kulo mjikelo sinokufumana amandla kwiimolekyuli zokutya okuphilayo. La mandla siwafumanayo sinokuwadlulisela kwiimolekyuli ukuze zisetyenziswe kwimisebenzi yeselula kwaye sinokwenza imisebenzi yethu ebalulekileyo kunye nayo yonke imisebenzi ebonakalayo yemihla ngemihla.
Ngaphakathi komjikelo we-krebs sifumana iimpendulo ezithile zeekhemikhali ikakhulu zi-oxidative kwindalo. Zonke iimpendulo zifuna ioksijini ukuze zenzeke. Impendulo nganye yemichiza inokuthatha inxaxheba kwezinye ii-enzymes ezifumaneka kwi-mitochondria yeeseli. Zonke ii-enzymes zinolona phawu luphambili lokukwazi ukuguqula ukusabela kwemichiza. Xa sithetha ngokuphembelela impendulo sibhekisa ekubeni sikwazi ukonyusa izinga apho izinto ezisabela ziguqulwa zibe yimveliso.
Amanyathelo omjikelo we krebs
Zininzi iindlela zokuphendula kwamachiza ngeli xesha lomjikelo ezifuna ukuba kwenziwe ioksijini. Impendulo yokuqala yamachiza kukuchithwa kwe-pyruvate ye-oxidative decarboxylation. Kule mpendulo, i-glucose efunyenwe ekuthotyeni kwe-hydrate ye-bald iguqulwa ibe ziimolekyuli ezimbini zepyruvic acid okanye ipyruvate. Iswekile yathotywa ngeGlycolysis kwaye iba ngumthombo obalulekileyo we-Acetyl-CoA. I-oxidative decarboxylation ye-pyruvate iqala ngomjikelo we-citric acid. Le mpendulo yamachiza ihambelana nokupheliswa kwekhabhon diokside kunye ne-pyruvate eveliswayo kwiqela le-acetyl elibophelela kwi-coenzyme A. Kule mpendulo yamachiza, i-NADH iveliswa njengemolekyuli ethwala amandla.
Nje ukuba imolekyuli ye-Acetyl-CoA yenziwe, kulapho umjikelo we-kreb wenzeka kwi-matrix ye-mitochondria. Injongo yeli candelo kukukwazi ukudibanisa ikhonkco ye-oxidation yeselfowuni yokwenza ioksijini zonke iikhabhoni kunye nokukwazi ukuziguqula zibe yicarbon dioxide. Ukuze kwenzeke zonke ezi zinto zivelayo, ubukho beoksijini bufuneka ngamaxesha onke. Ke, Sitshilo ngaphambi kokuqala ukuchaza umjikelo weKrebs ukubaluleka kokuphefumla kweselula.
Yonke le nto iqala nge-enzyme citrate synthetase ekhokelela ekuvuseleleni ukusabela kweekhemikhali apho ukuhanjiswa kweqela le-Acetyl ukuya kwi-asidi ye-oxaloacetic eyenza isenzo se-citric acid kunye nokukhululwa kwe-coenzyme A. Igama lalo mjikelo lihambelana ukwenziwa kwe-citric acid kunye nazo zonke iimpendulo zamachiza ezenzeka apha.
Ukuqhubela phambili i-oxidation kunye ne-decarboxylation reaction kwenzeka kula manyathelo alandelayo. Ezi mpendulo zibangela i-ketoglutaric acid ukuba yenze. Ngexesha lenkqubo, ikharbon diokside iyakhutshwa kwaye i-NADH kunye ne-H ziyenziwa.Le ketoglutaric acid ifumana i-oxidative decarboxylation reaction ethe yaphakanyiswa ngobunzima be-enzymatic apho i-Acetyl CoA kunye ne-NAD bayinxalenye. Zonke ezi mpendulo ziya kukhokelela kwi-acid ye-succinic, i-NADH, kunye nemolekyuli ye-GTP eya kuthi emva koko igqithisele amandla ayo kwimolekyuli ye-ADP evelisa i-ATP.
Amanyathelo okugqibela alo mjikelo ke bajolise kuphela kwinto yokuba i-acid ye-succinic inokufakwa i-oxidized ukwenza i-asidi ye-fumaric acid. Olu hlobo lweasidi lwaziwa ngegama le-fumarate. Icoenzyme yayo yi-ADF. Nantsi i-FADH2 izakwenziwa, eyenye imolekyuli yokuhambisa amandla. Okokugqibela, i-asidi ye-fumaric ayithandeki ukuba ikwazi ukwenza i-malic acid ekwabizwa ngokuba yi-malate. Ukuphelisa umjikelo we krebs, I-Malic acid iqala ukwenza i-oxidize ukwenza ngokuthe ngcembe i-oxaloacetic acid. Ngale ndlela, umjikelo uqalwa kwakhona kwaye zonke iimpendulo esizikhankanyileyo zenzeka kwakhona kwasekuqaleni.
Ndiyathemba ukuba ngolu lwazi unokufunda ngakumbi malunga nomjikelo we-krebs kunye neempawu zayo.