H\u00fccre Zar\u0131 (Plazmalemma)<\/p>\n
Daha \u00f6nce \u0131\u015f\u0131k mikroskobuyla varl\u0131\u011f\u0131 saptanmas\u0131na kar\u015f\u0131n, elektronprotein, ya\u011f ve az miktarda karbonhidrat molek\u00fcllerinden (\u00f6zellikle memelilerde) meydana gelmi\u015ftir. H\u00fccre zar\u0131n\u0131n yap\u0131s\u0131 hakk\u0131nda ilk bilimsel model Danielli ve Dawson taraf\u0131dan ortaya konmu\u015f ve bir\u00e7ok biyolog taraf\u0131ndan uzunca bir s\u00fcre benimsenmi\u015ftir. Bu modele g\u00f6re h\u00fccre zar\u0131n\u0131n ortas\u0131nda bir fosfolipit (60 A\u00b0 kal\u0131nl\u0131\u011f\u0131nda) ve bunun her iki taraf\u0131nda da birer protein tabakas\u0131 (30 A\u00b0 kal\u0131nl\u0131klar\u0131nda) bulunur. Buna “Zar Birimi” denir.<\/p>\n
Danielli ve Dawson modelinin, h\u00fccrenin i\u015flevsel bir par\u00e7as\u0131 olan h\u00fccre zar\u0131n\u0131n i\u015fleyi\u015fini tam olarak a\u00e7\u0131klayamamas\u0131, bu konuda yeni modellerin geli\u015ftirilmesine neden olmu\u015ftur, \u00f6yleki h\u00fccre zar\u0131n\u0131n, iki taraf\u0131nda protein, ortada fosfolipit tabakas\u0131ndan ibaret bir yap\u0131 olmad\u0131\u011f\u0131; bir lipit denizinde y\u00fczen, proteinden ve glikoproteinlerden yap\u0131lm\u0131\u015f, alma\u00e7 denen \u00f6zel b\u00f6lgelerle d\u0131\u015far\u0131ya a\u00e7\u0131lan bir “Mozaik Zar Modeli”nden olu\u015ftu\u011fu anla\u015f\u0131lm\u0131\u015ft\u0131r. Mozaik Zar Modeli 1966 y\u0131l\u0131nda Singer ve Lenard taraf\u0131ndan ortaya \u00e7\u0131kar\u0131ld\u0131, ancak 1972 y\u0131l\u0131nda ayr\u0131nt\u0131l\u0131 olarak yay\u0131nland\u0131. Bu zar modeli ya da birimi t\u00fcm h\u00fccrelerin d\u0131\u015f zar\u0131nda ve i\u00e7teki organellerinin zarl\u0131 k\u0131s\u0131mlar\u0131nda (mitokondri \u00e7eperi, golgi, endoplazmik retikulum, \u00e7ekirdek zan gibi) benzerdir.<\/p>\n
Zar\u0131n yap\u0131s\u0131ndaki lipitler \u00e7o\u011funluk fosfolipitlerdir ve zar\u0131n orta k\u0131sm\u0131nda iki tabakal\u0131 olarak bulunur. Bir tabakadaki fosfolipidin suda erimez lipofil (apolar) kutbu (ya\u011f asitlerini ta\u015f\u0131yan polarize olmam\u0131\u015f kutbu) \u00f6b\u00fcr tabakadaki fosfolipidin lipofil kutbuna d\u00f6n\u00fckt\u00fcr. Dolay\u0131s\u0131yla \u0131\u015f\u0131nsal bir \u015fekilde lipofil kutuplar kar\u015f\u0131kar\u015f\u0131ya gelmi\u015ftir. Suda eriyen hidrofil (polar) kutuplar\u0131 ise d\u0131\u015fa d\u00f6n\u00fckt\u00fcr. Bu tabakalar, polipeptitterden meydana gelmi\u015f bloklarla ya da adac\u0131klarla kesilmi\u015ftir. Bu haliyle h\u00fccre zar\u0131, i\u00e7inde proteinlerden yap\u0131lm\u0131\u015f adalar ta\u015f\u0131yan bir lipit denizi gibi g\u00f6r\u00fcn\u00fcr.<\/p>\n
Hayvansal h\u00fccrelerin d\u0131\u015f y\u00fcz\u00fc, h\u00fccre zar\u0131nda bulunan n\u00f6raminik asidin iyonize olmu\u015f karboksil grubundan dolay\u0131 eksi y\u00fckl\u00fcd\u00fcr. N\u00f6ramin, n\u00f6raminidaz enzimi ile zardan kopar\u0131l\u0131rsa, eksi y\u00fck\u00fcn b\u00fcy\u00fck bir k\u0131sm\u0131 yitirilir.<\/p>\n
Zar proteinleri, yerle\u015fim durumlar\u0131na g\u00f6re iki k\u0131sma ayr\u0131l\u0131r. Bir grup protein, ya\u011f tabakas\u0131n\u0131n her iki y\u00fcz\u00fcndedir. Bunlara “Ekstrinsik Proteinler” denir. Bir k\u0131sm\u0131 da ya\u011f tabakas\u0131n\u0131n i\u00e7ine g\u00f6m\u00fclm\u00fc\u015ft\u00fcr; d\u0131\u015f k\u0131s\u0131mlar\u0131 ya\u011f tabakas\u0131n\u0131n i\u00e7 ya da d\u0131\u015f y\u00fcz\u00fcne a\u00e7\u0131labilir. Bunlara da “l n t r i n s i k Proteinler” denir. intrinsik proteinlerden rodopsin retinan\u0131n \u00e7omak\u00e7\u0131klar\u0131ndaki taraklarda bulunur. Karanl\u0131kta 1 \/3’\u00fc oran\u0131nda. ayd\u0131nl\u0131kta ise 1 \/2’si oran\u0131nda zar i\u00e7ine g\u00f6m\u00fcl\u00fcr. Ekstrinsik proteinler sulu ortamla temas halinde olduklar\u0131 i\u00e7in hidrofilik amino asitleri, intrinsik proteinler ise bir taraflar\u0131 ile ya\u011f tabakas\u0131na g\u00f6m\u00fcl\u00fc olduklar\u0131 i\u00e7in bu k\u0131s\u0131mlar\u0131nda hidrofobik amino asitleri, di\u011fer taraflar\u0131 sulu ortamla temasta oldu\u011fu i\u00e7in de o taraflar\u0131nda hidrofilik amino asitleri ta\u015f\u0131rlar.<\/p>\n
Memeli h\u00fccrelerinde, \u00f6zellikle alyuvarlarda, intrinsik proteinlere ba\u011fl\u0131 olarak karbonhidratlar bulunmu\u015ftur. Karbonhidratlar, h\u00fccre zar\u0131nda glikoproteinler ve glikolipitler halinde bulunurlar ve zar y\u00fczeyinin, t\u00fcrlere hatta h\u00fccre gruplanna ili\u015fkin \u00f6zg\u00fcll\u00fc\u011f\u00fcn\u00fc sa\u011flarlar. Organellerin zar\u0131nda karbonhidrat bulunamam\u0131\u015ft\u0131r. H\u00fccre y\u00fczeyinde ince bir film halinde bulunan glikoproteinler h\u00fccreye antijenvir\u00fcs almac\u0131 olarak da kullan\u0131l\u0131rlar. Alyuvarlardaki mukopolisakkaritler antijen \u00f6zelli\u011finin yan\u0131s\u0131ra, kan gruplann\u0131n olu\u015fumunu da sa\u011flar. Bu karbonhidrat gruplar\u0131n\u0131n bozulmas\u0131 (kanserle\u015fme) ya da bir \u00e7e\u015fit a\u015f\u0131nmas\u0131, yani h\u00fccre zar\u0131n\u0131n ketle\u015fmesi, ya\u015flanmaya yol a\u00e7ar. \u00f6zellikle kanserle\u015fmede h\u00fccre y\u00fczeyi daha fazla eksi elektrik y\u00fckl\u00fc olur.<\/p>\n
\u00c7ok h\u00fccrelilerde h\u00fccrelerin birbirine temas\u0131 baz\u0131 bilgilerin aktar\u0131lmas\u0131na, \u00f6rne\u011fin h\u00fccre b\u00f6l\u00fcnmesinin durdurulmas\u0131na “Kontak inhibisyon”, morfo-genetik h\u00fccre hareketlerinin meydana gelmesine, b\u00fcy\u00fcmenin d\u00fczenlenmesine neden olur. Kontak inhibisyona g\u00fczel bir \u00f6rnek de, plazmodyumun (s\u0131tma etkeni) eritrositleri tan\u0131mas\u0131d\u0131r. Bu tan\u0131may\u0131 glikokalikslerle yapar. Di\u011fer bir\u00e7ok h\u00fccre paraziti ayn\u0131 y\u00f6ntemi kullan\u0131r.<\/p>\n
H\u00fccrenin i\u00e7 ortam\u0131n\u0131 d\u0131\u015f ortamdan ay\u0131ran ve her iki ortam aras\u0131ndaki madde al\u0131\u015fveri\u015fini d\u00fczenleyen h\u00fccre zar\u0131n\u0131n yap\u0131s\u0131 b\u00fcy\u00fck bir olas\u0131l\u0131kla sabit de\u011fildir. Ya\u011f ve protein molek\u00fclleri belirli s\u0131n\u0131rlar i\u00e7inde hareket eder. Bu hareket i\u00e7e ve d\u0131\u015fa do\u011fru olmaktan ziyade yanlara do\u011frudur. H\u00fccre zar\u0131n\u0131n yap\u0131sal de\u011fi\u015fimi, ta\u015f\u0131d\u0131\u011f\u0131 doymu\u015f ve doymam\u0131\u015f ya\u011f molek\u00fcllerinin miktar\u0131na ba\u011fl\u0131d\u0131r. Zar, genellikle v\u00fccut s\u0131cakl\u0131\u011f\u0131nda ak\u0131c\u0131 olan doymam\u0131\u015f ya\u011f molek\u00fcllerini i\u00e7erir. Zar y\u00fczeyinde mozaik \u015feklinde bulunan protein ve glikoprotein adac\u0131klar\u0131, etraf\u0131n\u0131 \u00e7eviren bir s\u0131ral\u0131 ya\u011f molek\u00fclleri ile s\u0131k\u0131ca ba\u011flanm\u0131\u015ft\u0131r (bu ikisinin aras\u0131nda hareket meydana gelmez). Fakat di\u011fer ya\u011f molek\u00fclleriyle ba\u011flant\u0131s\u0131 gev\u015fektir.<\/p>\n
H\u00fccre zar\u0131n\u0131n biyolojik etkinli\u011fini de\u011fi\u015ftiren bir\u00e7ok madde, \u00f6rne\u011fin karsinojen (kanserle\u015fmeye neden olurlar) maddeler, baz\u0131 hastal\u0131klar\u0131n ortaya \u00e7\u0131kmas\u0131na neden olmaktad\u0131r.<\/p>\n
H\u00fccre zar\u0131n\u0131n enine kesitlerinde, boylar\u0131 75 A0 kadar olabilen baz\u0131 kanallar\u0131n, d\u0131\u015f y\u00fczeyden i\u00e7 y\u00fczeye kadar uzand\u0131\u011f\u0131 saptanm\u0131\u015ft\u0131r. Elektron mikroskobuyla yap\u0131lan son \u00e7al\u0131\u015fmalarda, h\u00fccre zar\u0131n\u0131n, Golgi ayg\u0131t\u0131n\u0131n bir \u00fcr\u00fcn\u00fc oldu\u011fu saptanm\u0131\u015ft\u0131r. Golgi ayg\u0131t\u0131ndan kesecikler \u015feklinde s\u00fcrekli meydana gelen zar ak\u0131m\u0131, h\u00fccre zar\u0131n\u0131n k\u0131smi onar\u0131m\u0131nda ve h\u00fccre b\u00f6l\u00fcnmesinden sonra h\u00fccre zar\u0131n\u0131n b\u00fcy\u00fcmesinde kullan\u0131l\u0131r. H\u00fccre zar\u0131nda \u00e7ekirdek zar\u0131nda bulunan porlar bulunmaz. H\u00fccreye giren besinleri ve h\u00fccreden \u00e7\u0131kan art\u0131k maddeleri; zar\u0131n ge\u00e7irgenli\u011fi, \u00fc\u00e7 tabakal\u0131 molek\u00fcler dizili\u015fi ve \u00f6zellikle proteinden olu\u015fmu\u015f alma\u00e7 (resept\u00f6r) k\u0131s\u0131mlar\u0131 saptamakla beraber, elektriksel y\u00fck\u00fcn de bu giri\u015f-\u00e7\u0131k\u0131\u015fta b\u00fcy\u00fck bir \u00f6nemi oldu\u011fu varsay\u0131lmaktad\u0131r. H\u00fccre i\u00e7i ile d\u0131\u015f ortam aras\u0131ndaki elektrik potansiyel fark\u0131 (m V d\u00fczeyinde), baz\u0131 maddelerin i\u00e7eriye ve d\u0131\u015far\u0131ya pompalanmas\u0131n\u0131 kolayla\u015ft\u0131r\u0131r.<\/p>\n
Bir amip ya da silli hayvan yaralan\u0131rsa; bu yara yeni bir zarla hemen kapat\u0131l\u0131r. Bu yeni zara plazmalemma denir. Plazmalemmay\u0131 h\u00fccre aras\u0131na salg\u0131lanan maddelerle ya da bir \u00e7e\u015fit h\u00fccre iskeletini olu\u015fturan h\u00fccre d\u0131\u015f\u0131ndaki daha kat\u0131 sel\u00fcloz (bitkilerde) ya da mukopolisakkarit ve albuminoid yap\u0131larla kar\u0131\u015ft\u0131rmamak gerekir.<\/p>\n
H\u00fccre, yo\u011funlu\u011fu az olan bir s\u0131v\u0131 i\u00e7erisine (hipotonik) konursa \u015fi\u015fer ve sonunda patlar, buna “Hemoliz” (genellikle alyuvarlarda hemin h\u00fccre d\u0131\u015f\u0131na \u00e7\u0131kmas\u0131nda kullan\u0131l\u0131r); yo\u011funlu\u011fu fazla bir s\u0131v\u0131 i\u00e7erisine konursa, su kaybederek b\u00fcz\u00fcl\u00fcr, h\u00fccre zar\u0131 bitkilerde sel\u00fcloz duvardan ayr\u0131l\u0131r ve sonunda yine patlar buna da “Plazmoliz” denir.<\/p>\n","protected":false},"excerpt":{"rendered":"
H\u00fccre Zar\u0131 (Plazmalemma) Daha \u00f6nce \u0131\u015f\u0131k mikroskobuyla varl\u0131\u011f\u0131 saptanmas\u0131na kar\u015f\u0131n, elektronprotein, ya\u011f ve az miktarda karbonhidrat molek\u00fcllerinden (\u00f6zellikle memelilerde) meydana gelmi\u015ftir. H\u00fccre zar\u0131n\u0131n yap\u0131s\u0131 hakk\u0131nda ilk bilimsel model Danielli ve Dawson taraf\u0131dan ortaya konmu\u015f ve bir\u00e7ok biyolog taraf\u0131ndan uzunca bir s\u00fcre benimsenmi\u015ftir. Bu modele g\u00f6re h\u00fccre zar\u0131n\u0131n ortas\u0131nda bir fosfolipit (60 A\u00b0 kal\u0131nl\u0131\u011f\u0131nda) ve bunun …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1407,1403],"tags":[5627,6124,5306,2531,2549,4486,5623,2466,6278,2559,2303,2113],"class_list":["post-2515","post","type-post","status-publish","format-standard","hentry","category-fen-ve-teknoloji-odevleri","category-odevler","tag-alyuvar","tag-fosfolipit","tag-hidrofil","tag-hucre-zari","tag-karbonhidrat","tag-lipit","tag-mikroskob","tag-mitokondri","tag-plazmalemma","tag-plazmodyum","tag-protein","tag-yag"],"_links":{"self":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts\/2515","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/comments?post=2515"}],"version-history":[{"count":0,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts\/2515\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/media?parent=2515"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/categories?post=2515"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/tags?post=2515"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}