Isakhiwo kanye Nomsebenzi Wezingqimba Zeseli Ekuthuthweni Kwezidakamizwa
I-membrane yeseli, eyaziwa nangokuthi i-plasma membrane, isebenza njengesivikelo esibalulekile esihlukanisa izingxenye zangaphakathi zeseli endaweni yalo yangaphandle. Ayigcini nje ngokuhlinzeka ngokusekelwa nokuvikelwa kwesakhiwo kodwa futhi idlala indima ebalulekile ekulawuleni ukuthuthwa kwezinto zingene futhi ziphume eseli. Lesi sihloko sihlola isakhiwo esiyinkimbinkimbi se-membrane yeseli futhi sihlola imisebenzi yazo ekuthuthweni kwezinto, sikhanyise izindlela ezibalulekile ezigcina i-homeostasis yeseli.
Ukwakheka Kwama-Membrane Eseli
I-Phospholipid Bilayer
Isakhiwo esiyinhloko se-membrane yeseli yi-bilayer ye-phospholipid, equkethe izendlalelo ezimbili zama-molecule e-phospholipid. I-molecule ngayinye ye-phospholipid i-amphipathic, equkethe "ikhanda" eliheha amanzi kanye "nomsila" othanda amanzi. Endaweni enamanzi, imisila ethanda amanzi ibheke ngaphakathi, ivikelwe emanzini, kuyilapho amakhanda athanda amanzi ebheke ngaphandle, ehlangana nendawo ezungezile enamanzi ezinhlangothini zombili ze-membrane. Lokhu kuhlelwa kudala isithiyo esingangeni kancane esiyisisekelo somsebenzi we-membrane.
Amaprotheni
Kufakwe ngaphakathi kwe-bilayer ye-phospholipid kunamaprotheni amaningi enza imisebenzi eyahlukahlukene. Lawa maprotheni angahlukaniswa ngamaphrotheni abalulekile (angaphakathi) kanye nawangaphandle (angaphandle). Amaprotheni abalulekile ahlanganisa lonke ulwelwesi futhi ahilelekile kuma-molecule okuthutha kanye nokudluliselwa kwesignali. Ngakolunye uhlangothi, amaprotheni angaphandle anamathele ezindaweni zangaphandle noma zangaphakathi zolwelwesi, edlala indima ekugcineni isimo seseli futhi ehlinzeka ngendawo yokubeka ama-molecule ahlukahlukene okubonisa izimpawu.
carbohydrate
Ama-molecule e-carbohydrate avame ukunamathelana ndawonye namaprotheni (ama-glycoprotein) noma ama-lipid (ama-glycolipid) ohlangothini olungaphandle kwe-membrane. Lawa ma-carbohydrate adlala indima ebalulekile ekuqaphelweni kwamaseli, ukuxhumana, kanye nokunamathela. I-glycocalyx (indawo ecebile ngama-carbohydrate) idlala indima ebalulekile ekuvikeleni amaseli kanye nokwenza kube lula ukusebenzisana namanye amaseli kanye ne-extracellular matrix.
Cholesterol
Ama-molecule e-cholesterol afakwe ngaphakathi kwe-bilayer ye-phospholipid anezela ukuqina nokugeleza ku-membrane. Ngokuhlangana phakathi kwama-phospholipid, i-cholesterol isiza ukugcina ubuqotho be-membrane kanye nokuguquguquka kwayo kuzo zonke izinhlobo zokushisa.
Imisebenzi Yamaseli Ezakhi Zomzimba Ekuthuthweni Kwezinto Eziyingozi
Indlela i-membrane yeseli ekwazi ukungena kalula ngayo ivumela ukuthi ilawule ngokukhetha ukuhamba kwezinto zingene futhi ziphume eselini. Kunezindlela eziningana lapho i-membrane ifinyelela khona lo mthetho:
Ezokuthutha Ezingasebenzi
Ukusabalalisa Okulula
Ukusabalalisa okulula inqubo lapho ama-molecule asuka endaweni yokuhlushwa okuphezulu aye endaweni yokuhlushwa okuphansi ngaphandle kosizo lwamaprotheni e-membrane noma ukufakwa kwamandla. Ama-molecule amancane, angewona ama-polar njenge-oxygen ne-carbon dioxide angasabalala ngqo ku-phospholipid bilayer ngenxa yokuhambisana kwawo nomgogodla we-hydrophobic.
Ukusabalala Okulula
Ukusabalala okulula kuhilela nokuhamba kwezinto phansi kwe-gradient yazo yokuhlushwa kodwa kudinga usizo lwamaprotheni athile okuthutha. Amaprotheni esiteshi akha ama-pores ku-membrane, okuvumela ama-ion noma ama-molecule amanzi ukuba adlule. Amaprotheni okuthwala, ngakolunye uhlangothi, ashintsha ukwakheka kwawo ukuze athuthe ama-molecule amakhulu noma aphansi, njenge-glucose nama-amino acid, kulo lonke ulwelwesi.
Ezokuthutha Ezisebenzayo
Ngokungafani nokuthutha okwenziwa ngaphandle kokwenza lutho, ukuthutha okusebenzayo kudinga amandla, ngokuvamile ngesimo se-adenosine triphosphate (ATP), ukuhambisa izinto ngokumelene nokuphakama kwazo kokuhlushwa. Lokhu kubalulekile ekugcineni umehluko wokuhlushwa obalulekile emisebenzini yamaseli.
Ezokuthutha Ezisebenzayo Eziyinhloko
Ukuthutha okusebenzayo okuyinhloko kuhilela ukusetshenziswa okuqondile kwe-ATP ukuze kufakwe amandla ekuthuthweni kwezinto. Iphampu ye-sodium-potassium (iphampu ye-Na+/K+) iyisibonelo esaziwayo, lapho i-ATP isetshenziselwa ukupompa ama-ion e-sodium aphume esitokisini kanye nama-ion e-potassium angene esitokisini, kugcinwa ama-gradients abalulekile e-electrochemical.
Ezokuthutha Ezisebenzayo Zesibili
Ukuthutha okusebenzayo kwesibili, okwaziwa nangokuthi ukuthutha ngokubambisana, kuncike emandleni agcinwe ku-gradient yento eyodwa ukuze kuqhutshwe ukuthutha kwenye. Lokhu kungenzeka ngezindlela ezimbili: i-symport, lapho zombili izinto zihamba khona ngendlela efanayo, kanye ne-antiport, lapho zihamba khona ngezindlela eziphambene. I-sodium-glucose co-transporter iyisibonelo se-symport, isebenzisa i-sodium gradient esungulwe ukuthutha okusebenzayo okuyinhloko ukungenisa i-glucose ngokumelene ne-gradient yayo yokuhlushwa.
Ezokuthutha Ngenqwaba
Ukuze kuhambisane nama-molecule noma izinhlayiya ezinkulu, amaseli asebenzisa izindlela zokuthutha ngobuningi njenge-endocytosis kanye ne-exocytosis.
I-Endocytosis
I-Endocytosis inqubo lapho amaseli egwinya izinto zangaphandle ngokuzisonga ezingxenyeni ze-membrane yeseli, bese zincipha ukuze zakhe ama-vesicle ngaphakathi kweseli. Kunezinhlobo ezahlukene ze-endocytosis:
– I-Phagocytosis: “Ukudla kwamangqamuzana,” lapho izinhlayiya ezinkulu noma amangqamuzana zigcwala khona.
– I-Pinocytosis: “Ukuphuza amangqamuzana,” lapho iseli lithatha khona uketshezi olungaphandle kweseli kanye nezinto ezincibilikisiwe.
– I-Endocytosis Ephakathi Kwama-Receptor: Ifomu eliqondile kakhulu lapho amaprotheni ama-receptor ebusweni beseli ebopha khona ezintweni ezithile ngaphambi kokufakwa ngaphakathi.
I-Exocytosis
I-Exocytosis inqubo ephambene ne-endocytosis, lapho amangqamuzana ekhipha khona ama-molecule noma izinhlayiya ezinkulu ngokuhlanganisa ama-vesicle aqukethe izinto ne-membrane yeseli. Le ndlela ibalulekile ekukhipheni ama-neurotransmitters, ama-hormone, nama-enzyme okugaya ukudla.
Isiphetho
I-membrane yeseli iyisakhiwo esiguquguqukayo nesiyinkimbinkimbi esiyisisekelo empilweni yeseli. Njengoba ihlanganisa i-bilayer ye-phospholipid enamaprotheni afakiwe, ama-carbohydrate, kanye ne-cholesterol, isebenza njengesivimbelo esikhethiwe kanye nesixhumi sokuxhumana. Indima yayo ekuthuthweni kwezinto inezici eziningi, ehilela izindlela ezingasebenzi nezisebenzayo kanye nezinqubo zokuthutha ngobuningi. Ngokulawula kahle ukunyakaza kwama-molecule, i-membrane yeseli iqinisekisa ukugcinwa kwendawo yangaphakathi ezinzile, okwenza amaseli akwazi ukwenza imisebenzi yawo ehlukahlukene ngempumelelo. Ukuqonda isakhiwo kanye nemisebenzi yokuthutha kwama-membrane eseli akugcini nje ngokunikeza ukuqonda nge-physiology yamaseli kodwa futhi kubeka isisekelo sentuthuko ekusetshenzisweni kwezokwelapha kanye ne-biotechnology.
