V\u0130R\u00dcSLER<\/p>\n
Vir\u00fcsler yery\u00fcz\u00fcn\u00fcn bug\u00fcne kadar tan\u0131nm\u0131\u015f en k\u00fc\u00e7\u00fck canl\u0131lar\u0131 olarak kabul edilir. Vir\u00fcs zehir anlam\u0131na gelen Latince bir kelimedir.
\n19. y\u00fcz y\u0131lda L. Pasteur ve R. Koch gibi \u00f6nc\u00fc bakteriyologlar insan ve di\u011fer canl\u0131larda g\u00f6r\u00fclen bir \u00e7ok hastal\u0131klara bakterilerin sebep olduklar\u0131n\u0131 g\u00f6rm\u00fc\u015fler, fakat baz\u0131 hastal\u0131klarda onlar\u0131 \u015fa\u015f\u0131rtm\u0131\u015ft\u0131r. \u00c7\u00fcnk\u00fc hasta olan canl\u0131da, hastal\u0131\u011fa sebep olabilecek herhangi bir bakteri veya ba\u015fka bir organizma bulamam\u0131\u015flard\u0131r. B\u00f6yle bir hastal\u0131k ilk defa t\u00fct\u00fcn bitkisinde g\u00f6r\u00fclm\u00fc\u015ft\u00fcr. Hasta bitkinin yapraklar\u0131 buru\u015fur, lekelenir, zamanla mozaik g\u00f6r\u00fcn\u00fc\u015f\u00fcn\u00fc al\u0131r. Bu nedenle hastal\u0131\u011fa mozaik hastal\u0131\u011f\u0131 denilmi\u015ftir.<\/p>\n
1892 y\u0131l\u0131nda ivanowsky(ivanovski) ad\u0131nda bir Rus bilgini vir\u00fcslerin porselen s\u00fczge\u00e7lerden ge\u00e7ti\u011fini ispatlam\u0131\u015f (porselen s\u00fczge\u00e7ten bakteriler ge\u00e7emez), Hollandal\u0131 mikro biyolog W. Beijernik(bayernik) de t\u00fct\u00fcn bitkisindeki hastal\u0131k fakt\u00f6r\u00fcn\u00fc (hastal\u0131k yapan canl\u0131 s\u0131v\u0131 ) olarak adland\u0131rm\u0131\u015ft\u0131r.20. y\u00fczy\u0131l\u0131n ba\u015flar\u0131nda porselen kaplarda filitre edilerek akterilerden tamamiyle izole edildi\u011fi halde yine sa\u011flam olan bitki ve hayvanlar\u0131n hastalanmas\u0131na sebep olmu\u015ftur. Bu \u00e7al\u0131\u015fmalar sonucu t\u00fct\u00fcn mozaik vir\u00fcs\u00fcnden ba\u015fka patates vir\u00fcs\u00fc, salatal\u0131k mozaik vir\u00fcs\u00fc , marul mozaik vir\u00fcs\u00fc gibi bir\u00e7ok bitkilerdeki \u00e7e\u015fitli hastal\u0131klarla, insanlarda g\u00f6r\u00fclen grip, nezle, k\u0131zam\u0131k, su\u00e7i\u00e7e\u011fi, kabakulak, kuduz ve \u00e7ocuk felci gibi hastal\u0131klar\u0131 vir\u00fcslerin yapt\u0131klar\u0131 anla\u015f\u0131lm\u0131\u015ft\u0131r.<\/p>\n
V\u0130R\u00dcSLER\u0130N B\u00dcY\u00dcKL\u00dc\u011e\u00dc VE \u015eEKL\u0130:
\n B\u00fct\u00fcn vir\u00fcsler o kadar k\u00fc\u00e7\u00fckt\u00fcr ki , bunlar \u0131\u015f\u0131k mikroskobunda belirli .\u015fekilde g\u00f6r\u00fclmektedir.B\u00fcy\u00fckl\u00fckleri genel olarak 15-450 milimikron aras\u0131nda de\u011fi\u015fir . \u00c7ocuk felci vir\u00fcs\u00fcn\u00fcn elektron mikroskobuyla al\u0131nan foto\u011fraf\u0131 vir\u00fcs par\u00e7ac\u0131klar\u0131n\u0131n pinpon toplar\u0131na benzer minik yuvarlaklar halinde oldu\u011funu g\u00f6stermi\u015ftir.<\/p>\n
V\u0130R\u00dcSLER\u0130N YAPISI:
\nBiyologlar vir\u00fcsleri canl\u0131 tabiat\u0131n e\u015fi\u011finde yani en alt basama\u011f\u0131nda bulunan varl\u0131klar olarak kabul ederler. \u00c7ok k\u00fc\u00e7\u00fck \u00e7ok ilkesel organizmalard\u0131r. Bu bak\u0131mdan vir\u00fcsler hakk\u0131ndaki bilgilerimiz hen\u00fcz \u00e7ok de\u011fildir.biyologlar \u00e7ok ince ve dikkatli ara\u015ft\u0131rmalar\u0131 sonucu vir\u00fcslerin bir n\u00fckleik asit RNA \u00f6z maddesi ile bunu saran bir prote\u011fin k\u0131l\u0131f\u0131ndan meydana geldi\u011fini bulmu\u015flard\u0131r. \u00d6z madde vir\u00fcs\u00fcn \u00e7e\u015fidine g\u00f6re bir RNA veya DNA olabilir.<\/p>\n
Yap\u0131s\u0131nda DNA bulunan bir vir\u00fcs \u00e7e\u015fidi vard\u0131r ki bunlar bakteri h\u00fccrelerine girer , onlar\u0131n i\u00e7inde \u00e7o\u011fal\u0131rlar. Bu vir\u00fcslere bakteriyofaj (yap\u0131s\u0131nda DNA bulunan bir vir\u00fcs \u00e7e\u015fidi vard\u0131r ki, bunlar bakteri h\u00fccrelerine girer ve onlar\u0131n i\u00e7inde \u00e7o\u011fal\u0131rlar. Bu vir\u00fcslere bakteriyofaj veya faj denir. ) denir. Bakteriyofajlar bakterilerileri yiyerek ya\u015farlar. Bakterilerin i\u00e7inde \u00fcrer ve en sonunda i\u00e7inde \u00fcrer ve en sonunda i\u00e7inde ya\u015fad\u0131klar\u0131 h\u00fccreyi yok ederler. \u0130nsan ve hayvanlarda hastal\u0131k yapan vir\u00fcslerin \u00e7o\u011fuda, etraf\u0131 prote\u011fin k\u0131l\u0131f ile \u00e7evrili DNA ipli\u011finden ba\u015fka bir \u015fey de\u011fildir.
\nV\u0130R\u00dcSLER\u0130N \u00dcREMES\u0130<\/p>\n
Bakteri h\u00fccrelerini yiyen vir\u00fcslerin, bakteri i\u00e7ine girdikleri zaman onlar\u0131 yedikleri bilinmektedir. Vir\u00fcs bakteri h\u00fccresine yakla\u015ft\u0131\u011f\u0131 zaman \u00f6nce kuyruk taraf\u0131yla tutunur. Sonra tek ve uzun olan DNA ipli\u011fi bakterinin i\u00e7ine g\u00f6nderir. Bakteri h\u00fccresinde, kendi hayat olaylar\u0131n\u0131 y\u00f6neten bakteriye has DNA \u2018da vard\u0131r . Ancak vir\u00fcs\u00fcn DNA\u2019s\u0131 h\u00fccreye girer girmez bakterinin yeni maddeler yapma i\u015fini kendi iste\u011fine g\u00f6re y\u00f6netmeye ba\u015flar, bakteri maddesini kullanarak vir\u00fcs maddesi yapmas\u0131n\u0131 sa\u011flar. B\u00f6ylece bakteri enzimlerinden faydalanarak, bakteri i\u00e7indeki maddeler vir\u00fcs DNA\u2019s\u0131 yap\u0131lmas\u0131nda kullan\u0131l\u0131r ve sonunda bakteri \u00f6l\u00fcr. Vir\u00fcs\u00fcn DNA\u2019s\u0131 bakteriye girmesinden hemen sonra, bu DNA yeni vir\u00fcsler yapmaya ba\u015flar. Yar\u0131m saatten daha az bir zaman i\u00e7inde bakteri h\u00fccresi par\u00e7alanarak, yeni meydana gelen y\u00fczlerce vir\u00fcs d\u0131\u015far\u0131 \u00e7\u0131kar. Bu ge\u00e7 vir\u00fcslerin her biri ba\u015fka bir bakteriye girmeye haz\u0131r demektir. B\u00f6ylece bir s\u00fcre sonra vir\u00fcs\u00fcn ya\u015fad\u0131\u011f\u0131 ortamdaki b\u00fct\u00fcn bakteriler yok olabilir. <\/p>\n
Vir\u00fcslerin Fiziksel \u00d6zellikleri:
\nGe\u00e7irgenli\u011fi bilinen kolodyum s\u00fczge\u00e7ler sayesinde vir\u00fcslerin b\u00fcy\u00fckl\u00fc\u011f\u00fc \u00f6l\u00e7\u00fclebilir ve 10 ile 300 nm aras\u0131nda oldu\u011fu g\u00f6r\u00fcl\u00fcr(Bakteriyofaj 10 ile 50 nm aras\u0131nda oldu\u011fu \u00e7ocuk felci vir\u00fcs\u00fc 15 nm harpas 300 nm vb.) Elektron mikroskobu bunlar\u0131n k\u00fcre bi\u00e7iminde oldu\u011funu g\u00f6sterir. Vir\u00fcsler bakteriyolojide kullan\u0131lan besiyerlerinde \u00fcretilememekte, yaln\u0131z baz\u0131 canl\u0131 dokularda \u00fcretilebilmektedir. \u2013 20\u00ba so\u011fukta tahrip olmazlar, ama s\u0131cakl\u0131\u011fa dayan\u0131kl\u0131 de\u011fildirler. Elektrik ak\u0131m\u0131na duyarl\u0131d\u0131rlar. Elektroferezle yerleri de\u011fi\u015ftirilebilir ve k\u00fclt\u00fcr ortam\u0131nda yal\u0131t\u0131labilirler. Radyasyonlara ve antiseptiklere az yada \u00e7ok duyarl\u0131d\u0131rlar. <\/p>\n
Vir\u00fcslerin yap\u0131s\u0131:
\nB\u00fct\u00fcn \u00f6teki canl\u0131lar\u0131nkinden daha basittir. Duruma g\u00f6re bir tek n\u00fckleik asit (DNA yada RNA zincirinden olu\u015ftuklar\u0131 kabul edilir. Bu zincir bir kabuk (kapsit) olu\u015fturan proteinlerle \u00e7evrilidir ama bu proteinler di\u011fer b\u00fct\u00fcn h\u00fccrelerde oldu\u011fu gibi vir\u00fcslerin kendileri taraf\u0131ndan sentezlenmez. Vir\u00fcs\u00fcn asalak oldu\u011fu h\u00fccrelerden kaynaklan\u0131r. Vir\u00fcs onlara bu sentez i\u00e7in gerekli enzimleri ve hammaddeleri (aminoasitler) verir. Yani vir\u00fcs ancak bir h\u00fccrenin (konak h\u00fccre) i\u00e7inde asalak olarak ya\u015fayabilir. Vir\u00fcs\u00fcn bir organizmadan di\u011ferine ge\u00e7mesi i\u00e7in, o vir\u00fcslere \u00f6zg\u00fc n\u00fckleik zincir (DNA yada RNA) ile son konakta edindi\u011fi protein kabuktan olu\u015fan vir\u00fcs par\u00e7ac\u0131klar\u0131n\u0131n rol oynad\u0131\u011f\u0131 kabul edilmektedir. Vir\u00fcs par\u00e7ac\u0131\u011f\u0131 ba\u015fka bir h\u00fccreye girer girmez k\u0131l\u0131f\u0131n\u0131 (kabu\u011funu) atar ve kona\u011f\u0131n metabolizmas\u0131na kar\u0131\u015farak onun DNA ya da RNA\u2019s\u0131yla birle\u015fir ve onda az yada \u00e7ok \u00f6nemli bozukluklara neden olur; e\u011fer metabolizma a\u011f\u0131r derecede bozulmu\u015fsa, h\u00fccre \u00f6l\u00fcr, vir\u00fcs yeniden \u00e7o\u011fal\u0131r ve bir \u00f6nceki h\u00fccrede edindi\u011fi kabukla ba\u015fka h\u00fccrelerede bula\u015f\u0131r; e\u011fer bozukluklar az \u00f6nemliyse i\u00e7lerinde vir\u00fcs bulunan h\u00fccreler vir\u00fcs\u00fcn \u00e7ekirdek k\u0131sm\u0131n\u0131 (yapay bir gen gibi) kendi kromozomlar\u0131na ekler ve atipik b\u00f6l\u00fcnebilen h\u00fccrelere,yani ur (kanser) h\u00fccrelerine d\u00f6n\u00fc\u015f\u00fcrler. Birinci grup olgulara vir\u00fcsl\u00fc bula\u015f\u0131c\u0131 hastal\u0131klar denir. (grip, sar\u0131humma, k\u0131zam\u0131k vb.) Vir\u00fcs\u00fcn girdi\u011fi organizman\u0131n h\u0131zla yaratt\u0131\u011f\u0131 ba\u011f\u0131\u015f\u0131kl\u0131k tepkimesinin, vir\u00fcs DNA ya da RNA\u2019s\u0131n\u0131n bir h\u00fccreden di\u011ferine ge\u00e7mek i\u00e7in sar\u0131nd\u0131\u011f\u0131 protein kabu\u011fa kar\u015f\u0131 oldu\u011fu san\u0131lmaktad\u0131r. Antikorlar bu kabuk sayesinde h\u0131zla vir\u00fcs par\u00e7ac\u0131\u011f\u0131n\u0131 bulur ve yok ederler. \u0130kinci grup olgularda birincisinin tersine, ba\u011f\u0131\u015f\u0131kl\u0131\u011f\u0131n olu\u015fmas\u0131 daha zordur, \u00e7\u00fcnk\u00fc DNA ya da RNA bireyin h\u00fccreleriyle birle\u015fmi\u015f ve bu nedenle korunmu\u015ftur. Baz\u0131 kanserlerin vir\u00fcslerden ileri geldi\u011fi yaln\u0131z hayvanlardaki (ku\u015flar) \u00e7e\u015fitli kanserlerde kesin olarak kan\u0131tlanm\u0131\u015ft\u0131r, ama insanlarda g\u00f6zlenen kanserlerde hen\u00fcz b\u00f6yle bir yarg\u0131ya var\u0131lamam\u0131\u015ft\u0131r.<\/p>\n
N\u00fckleik asitlerinin tipine (DNA ya da RNA) g\u00f6re vir\u00fcsler, iki grup halinde s\u0131n\u0131fland\u0131r\u0131l\u0131r. RNA\u2019n\u0131n DNA sentezleyebilece\u011fini vitro g\u00f6steren \u201cters transkriptaz\u201d \u0131n bulunmas\u0131, DNA\u2019lar olmaks\u0131z\u0131n bir genomla b\u00fct\u00fcnle\u015febilen baz\u0131 RNA\u2019l\u0131 vir\u00fcslerin etki bi\u00e7iminin anla\u015f\u0131lmas\u0131na olanak vermi\u015ftir. Rous sarkomu vir\u00fcs\u00fc gibi melez RNA-DNA kanser vir\u00fcsleri bu \u00e7e\u015fit vir\u00fcslerdir. <\/p>\n
Vir\u00fcs\u00fcn girdi\u011fi konak h\u00fccrenin g\u00f6sterdi\u011fi tepkimeler aras\u0131nda, yeni ke\u015ffedilen bir maddenin (interteron)olu\u015fumunu da saymak gerekir. B\u00fct\u00fcn bu kavramlar zaman i\u00e7inde, yollar\u0131 birbirine kavu\u015fan viroloji ve molek\u00fcller biyolojideki geli\u015fmeler sayesinde ortaya konmu\u015ftur. <\/p>\n
B\u00f6obil, insanda, hayvanlarda ya da bitkilerde hastal\u0131klara yol a\u00e7an bir\u00e7ok vir\u00fcs, eklembacakl\u0131lar ve \u00f6zelliklede b\u00f6cekler arac\u0131l\u0131\u011f\u0131yla bula\u015f\u0131r: sar\u0131humma vir\u00fcs\u00fc, bir memeli hayvandan (ara konak) ge\u00e7tikten sonra Aedes cinsinden bir sivrisinekle bula\u015f\u0131r. Patates k\u0131v\u0131rc\u0131k hastal\u0131\u011f\u0131 ve yaprak k\u0131vr\u0131lma hastal\u0131\u011f\u0131 vir\u00fcsleri bitki bitleriyle \u00f6zellikle Myzus persicae patatese ge\u00e7er bu b\u00f6cekler ta\u015f\u0131d\u0131klar\u0131 hastal\u0131klar bula\u015ft\u0131r\u0131rlar. Bula\u015fma s\u00fcreci vir\u00fcse ve onu ta\u015f\u0131yan b\u00f6ce\u011fe g\u00f6re farkl\u0131l\u0131k g\u00f6sterir.:arbo vir\u00fcslerin \u00e7o\u011fu sivrisineklerle, Phlebotolomu\u015f\u2019larla yada \u0131xoces\u2019lerle bula\u015f\u0131r.: t\u00fct\u00fcn hastal\u0131klar\u0131na yol a\u00e7an vir\u00fcsler \u00f6be\u011fi, \u015fekerpancar\u0131nda g\u00f6r\u00fclen sar\u0131l\u0131\u011f\u0131n tersine bitki bitleriyle ta\u015f\u0131nmaz. Baz\u0131 vir\u00fcsler hastal\u0131\u011f\u0131 bula\u015ft\u0131ran hayvanda (bitki biti, Cicadella. Aleurodes) uzun bir kulu\u00e7ka d\u00f6nemi ger\u00e7irebilir. Bu hayvan\u0131n bedeninde kalabilir, \u00e7o\u011falabilir ama baz\u0131lar\u0131n\u0131n kulu\u00e7ka d\u00f6nemi k\u0131sad\u0131r, bunlar\u0131 yapamaz. Akarlar,ikikanatl\u0131lar ve yar\u0131mkanatl\u0131lar d\u0131\u015f\u0131nda kalan b\u00f6cekler (baz\u0131 k\u0131nkanatl\u0131lar ve d\u00fcz kanatl\u0131lar) da vir\u00fcs bula\u015ft\u0131rabilir.<\/p>\n
DNA\u2019l\u0131 Vir\u00fcsler<\/p>\n
DNA\u2019l\u0131 Vir\u00fcsler \u00e7o\u011falabilmek i\u00e7in bakteri h\u00fccrelerinde veya \u00fcst\u00fcn yap\u0131l\u0131 canl\u0131lar\u0131 meydana getiren h\u00fccrelerde asalak ya\u015far.<\/p>\n
Vir\u00fcsler bir n\u00fckleik asit molek\u00fcl\u00fcnden ibaret (t\u00fcm genetik varl\u0131\u011f\u0131 budur) biyolojik organizmalard\u0131r. N\u00fckleik asit molek\u00fcl\u00fc proteinden bir kapsidin i\u00e7inde yer al\u0131r ve bu kapsit bazen bir k\u0131l\u0131fla kapl\u0131d\u0131r.<\/p>\n
DNA\u2019l\u0131 vir\u00fcsler aras\u0131nda, boylar\u0131 \u00e7ok k\u00fc\u00e7\u00fck olan Adeno-vir\u00fcsler (0,08 mikrometre, um) veya papovavir\u00fcsler (0,06 um) gibi vir\u00fcsler vard\u0131r. Oysa bir bakteri h\u00fccresi bir um ve bir memeli h\u00fccresi 5-10 um boyunda olabilir. Adenovir\u00fcsler insanlarda yutak, bademcik iltihaplar\u0131 ve solunum yolu hastal\u0131klar\u0131na yol a\u00e7ar; papovavir\u00fcslerden baz\u0131lar\u0131 si\u011file neden olur. Bu iki vir\u00fcs \u201c\u00e7\u0131plak\u201d vir\u00fcslerdendir, yani bunlar\u0131n kapsitinin etraf\u0131nda k\u0131l\u0131f bulunmaz; adenovir\u00fcslerin DNA\u2019s\u0131 40.000 n\u00fckleotitten papovavir\u00fcslerin DNA\u2019s\u0131ysa yaln\u0131z 5 000 ile 8 000 n\u00fckleositten olu\u015fur (bir bakteri DNA\u2019s\u0131 8 milyon, bir memeli h\u00fccresinin DNA\u2019s\u0131 3 milyar n\u00fckleotitden meydana gelir. DNA vir\u00fcslerinin en k\u00fc\u00e7\u00fc\u011f\u00fc hepatit B vir\u00fcs\u00fcd\u00fcr; boyu 0,04 nm\u2019dir ve DNA\u2019s\u0131 3 200 n\u00fckleotitten olu\u015fur. Adenovir\u00fcs ve papovavir\u00fcslerin tersine bunun kapsidi, lipit i\u00e7eren bir k\u0131l\u0131fla kapl\u0131d\u0131r. Ba\u015fka baz\u0131 DNA\u2019l\u0131 vir\u00fcslerin k\u0131l\u0131f\u0131 da lipittendir, ama bunlar biraz daha b\u00fcy\u00fckt\u00fcr. Mesela u\u00e7uk yapan herpes vir\u00fcs\u00fc 0,18um\u2019dir ve DNA\u2019s\u0131 200 000 n\u00fckleotitten meydana gelir; poksvir\u00fcs (\u00e7i\u00e7ek hastal\u0131\u011f\u0131 vir\u00fcs\u00fc gibi)0,2 um\u2019dir ve DNA\u2019s\u0131 300 000 n\u00fckleotitten olu\u015fur.<\/p>\n
Bakteriyelerde asalak ya\u015faya vir\u00fcslere bakteriyofaj (veya faj) denir. Bakteriyofajlar\u0131n kapsidi kuyru\u011fa benzeyen bir uzant\u0131yla sona erer. Vir\u00fcs, DNA\u2019s\u0131n\u0131 bu kanaldan bakteri h\u00fccresine aktar\u0131r.<\/p>\n
Bakteriyofajlardan fakl\u0131 olarak hayvan ve bitki vir\u00fcsleri, kapsit ve k\u0131l\u0131flar\u0131n\u0131n \u00fczerinde yer alan molek\u00fcllerin yard\u0131m\u0131yla konak h\u00fccrenin zar\u0131na tutunur ve endositozla (normal \u015fartlarda, h\u00fccrenin, metabolizmas\u0131 i\u00e7in gerekli olan besinleri i\u00e7eri almas\u0131na yarayan mekanizma) h\u00fccrenin i\u00e7ine girer.<\/p>\n
B\u00fct\u00fcn DNA\u2019l\u0131 vir\u00fcslerde ya\u015fam d\u00f6ng\u00fcs\u00fc birbirin ayn\u0131d\u0131r. Bu vir\u00fcsler \u00f6nce konak h\u00fccrenin \u00f6zel enzimlerinden yararlanarak kendi DNA molek\u00fclllerini e\u015fler ve \u00e7o\u011falt\u0131r. Daha sonra bu vir\u00fcs DNA\u2019lar\u0131n\u0131n yard\u0131m\u0131yla h\u00fccrenin haberci RNA\u2019lar\u0131n\u0131 kullanarak kendisine gerekli olan maddelerin ve kapsit proteinlerinin sentezini ger\u00e7ekle\u015ftirir.<\/p>\n
\u00c7ok say\u0131da \u00fcretilen kapsitler, konak h\u00fccrenin patlamas\u0131na yol a\u00e7ar. Kendisini e\u015flemi\u015f olan vir\u00fcs DNA\u2019lar\u0131 bu evrede kapsitlerin i\u00e7ine girer, yani kendine bir kapsit yapar ve konak h\u00fccre \u00f6l\u00fcnce d\u0131\u015far\u0131 \u00e7\u0131kar. Yeni olu\u015fan ve vir\u00fcslerin ba\u015fka h\u00fccrelere girmesiyle, s\u00f6z konusu d\u00f6ng\u00fc yeniden ba\u015flar (vir\u00fcs enfeksiyonlar\u0131nda, hastal\u0131\u011f\u0131n as\u0131l nedeni i\u015f bu konak h\u00fccre y\u0131k\u0131m\u0131d\u0131r). K\u0131l\u0131fl\u0131 vir\u00fcslerde d\u00f6ng\u00fcn\u00fcn son evresi biraz daha farkl\u0131 olarak geli\u015fir.: Bu vir\u00fcsler, konak h\u00fccreyi patlatarak de\u011fil, h\u00fccre zar\u0131n\u0131n bir k\u0131sm\u0131n\u0131 da alarak tomurcuklanma yoluyla d\u0131\u015far\u0131 \u00e7\u0131kar. Bu durumda, konak h\u00fccrenin tepkisi hastal\u0131\u011fa neden olur. Bu nedenle Epstein-Barr denilen herpes vir\u00fcs\u00fc veya papillom gibi d\u00f6lyata\u011f\u0131 boynu yaralar\u0131na yol a\u00e7an baz\u0131 vir\u00fcsler ile hepatit B vir\u00fcs\u00fc, v\u00fccutta kanserlerin olu\u015fumunda rol oynayan vir\u00fcslerdendir.<\/p>\n
RNA\u2019l\u0131 vir\u00fcsler<\/p>\n
Genetik varl\u0131\u011f\u0131 RNA molek\u00fcl\u00fcnden ibaret vir\u00fcslerin boylar\u0131 0,2 um (\u00e7ocuk felci vir\u00fcs\u00fc gibi pikorna vir\u00fcsler) ile 0,2 um (grip vir\u00fcs\u00fc gibi ortomikso vir\u00fcsler)aras\u0131nda de\u011fi\u015fir. Bunlar\u0131n genetik varl\u0131\u011f\u0131 genelikle k\u00fc\u00e7\u00fckt\u00fcr, asla 20000 n\u00fckleotti a\u015famaz. bunlardan pikorna vir\u00fcsler gibi baz\u0131lar\u0131 \u201c\u00e7\u0131plak\u201dvir\u00fcslerdir (yani kapsidi \u00e7evreleyen bir k\u0131l\u0131f\u0131 yoktur ) b\u00fcy\u00fck \u00e7o\u011funluysa lipit i\u00e7eren k\u0131l\u0131fla korunmu\u015ftur.<\/p>\n
Ba\u015fl\u0131ca 3 \u00e7e\u015fit RNA\u2019l\u0131 vir\u00fcs vard\u0131r: genetik yap\u0131s\u0131 tek zincirli RNA molek\u00fcl\u00fc i\u00e7eren ve bu molek\u00fcl\u00fc do\u011frudan haberci RNA gibi kullanan pozitif vir\u00fcsler; tek zincirli RNA molek\u00fcl\u00fc i\u00e7eren ama bunu haberci RNA gibi kullanamayan negatif vir\u00fcsler; son olarak haberci RNA i\u015flevi g\u00f6rmeyen,ama DNA molek\u00fcl\u00fc olarak kopyalanabilen tek zincirli pozitif RNA molek\u00fcl\u00fc i\u00e7eren vir\u00fcsler ki, bunlar konak h\u00fccrenin kromozomuyla kayna\u015farak h\u00fccrede, haberci RNA sentezini y\u00f6nete bilir . Retrovir\u00fcsler bu \u015fekilde etki g\u00f6stermektedir. <\/p>\n
Tek zincirli pozitif RNA vir\u00fcslerine \u00f6rnek olarak \u00e7ocuk felcinin ve daha ba\u015fka bir\u00e7ok hastal\u0131\u011f\u0131n sebebi olan sorumlu pikornavir\u00fcsler g\u00f6sterilebilir. Yakla\u015f\u0131k 6ila 8 saat kadar sonra, konak h\u00fccre patlar ve say\u0131lar\u0131 100000\u2019e yak\u0131n yeni vir\u00fcs (kapsit+RNA) a\u00e7\u0131\u011fa \u00e7\u0131kar .<\/p>\n
\u0130kinci grupta grip vir\u00fcs\u00fc gibi ortomikso vir\u00fcsler veya kuduz vir\u00fcs\u00fc gibi rabdovir\u00fcsler yer al\u0131r. Bu vir\u00fcslerde transkriptaz ad\u0131 verilen bir enzim bulunur. Vir\u00fcs h\u00fccreye girdi\u011finde, RNA negatif vir\u00fcs zinciri, traskriptaz sayesinde pozitif RNA zincirine d\u00f6n\u00fc\u015f\u00fcr. Bu pozitif RNA zinciri ya haberci RNA i\u015f g\u00f6r\u00fcr yada do\u011frudan genetik maddenin \u00e7o\u011falmas\u0131 i\u00e7in kal\u0131p \u00f6devi g\u00f6rmeye ba\u015flar. Vir\u00fcs prote\u011finlerin ve yeni RNA zincirlerinin sentezlenmesiyle \u00e7ok say\u0131da yeni vir\u00fcs meydana gelir ve bunlar tomurcuklanma yoluyla konak h\u00fccreden d\u0131\u015far\u0131 \u00e7\u0131kar . bu s\u0131rada vir\u00fcs h\u00fccre zar\u0131n\u0131n bir b\u00f6l\u00fcm\u00fcn\u00fc de beraberinde g\u00f6t\u00fcr\u00fcrse k\u0131l\u0131fl\u0131 vir\u00fcs olur.<\/p>\n
\u00dc\u00e7\u00fcnc\u00fc kategorideki retrovir\u00fcslerde ters transkriptaz ad\u0131 verilen bir enzim bulunur. Vir\u00fcs konak h\u00fccreye girdi\u011finde, bu enzim yard\u0131m\u0131yla RNA molek\u00fcl\u00fcnden DNA molek\u00fcl\u00fcn\u00fcn traskripsiyonu ger\u00e7ekle\u015fir. Bu taktirde vir\u00fcs DNA\u2019s\u0131 konak h\u00fccrenin kromozom DNA\u2019s\u0131yla kayna\u015fabilir; o zaman bu molek\u00fcle provir\u00fcs DNA\u2019s\u0131 hem haberci RNA molek\u00fcl\u00fcn\u00fcn hemde kapsit prote\u011finlerinin sentezini y\u00f6netir. Yeni sentezlenen RNA molek\u00fcleri kapsitlerle paketlenerek tomurcuklanma sonucu h\u00fccreden d\u0131\u015far\u0131 \u00e7\u0131kar.<\/p>\n
AIDS vir\u00fcs\u00fc de retrovir\u00fcsler grubundand\u0131r. Ayr\u0131ca hayvanlar \u00fczerinde yap\u0131lan deneyler sonucu l\u00f6semi ve kansere yol a\u00e7an retrovir\u00fcsler de bulunmu\u015ftur. Bu vir\u00fcslere onkojen ad\u0131 verilen \u00f6zel bir gen bulundu\u011fu ve bu genin konak h\u00fccre kromozonuna kat\u0131ld\u0131\u011f\u0131nda h\u00fccrenin kanserle\u015fmesine yol a\u00e7an bir prote\u011fini sentezledi\u011fi bulunmaktad\u0131r.<\/p>\n","protected":false},"excerpt":{"rendered":"
V\u0130R\u00dcSLER Vir\u00fcsler yery\u00fcz\u00fcn\u00fcn bug\u00fcne kadar tan\u0131nm\u0131\u015f en k\u00fc\u00e7\u00fck canl\u0131lar\u0131 olarak kabul edilir. Vir\u00fcs zehir anlam\u0131na gelen Latince bir kelimedir. 19. y\u00fcz y\u0131lda L. Pasteur ve R. Koch gibi \u00f6nc\u00fc bakteriyologlar insan ve di\u011fer canl\u0131larda g\u00f6r\u00fclen bir \u00e7ok hastal\u0131klara bakterilerin sebep olduklar\u0131n\u0131 g\u00f6rm\u00fc\u015fler, fakat baz\u0131 hastal\u0131klarda onlar\u0131 \u015fa\u015f\u0131rtm\u0131\u015ft\u0131r. \u00c7\u00fcnk\u00fc hasta olan canl\u0131da, hastal\u0131\u011fa sebep olabilecek herhangi …<\/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":[8027,8006,6217,5938,8024,8022,2286,5781,8019,2281,8023,8026,8025,8018,2279,8020,8021],"class_list":["post-3504","post","type-post","status-publish","format-standard","hentry","category-fen-ve-teknoloji-odevleri","category-odevler","tag-aids-virusu","tag-bakteri-hucreleri","tag-bakteriyofaj","tag-biyolog","tag-cicek-hastaligi-virusu","tag-dnali-virusler","tag-elektron-mikroskobu","tag-kromozomlar","tag-marul-mozaik-virusu","tag-nukleik-asitler","tag-poksvirus","tag-retrovirusler","tag-rnali-virusler","tag-salatalik-mozaik-virusu","tag-virusler","tag-viruslerin-fiziksel-ozellikleri","tag-viruslerin-yapisi"],"_links":{"self":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts\/3504","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=3504"}],"version-history":[{"count":0,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts\/3504\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/media?parent=3504"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/categories?post=3504"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/tags?post=3504"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}