Genetik, (Yunanca’dan genno #947; #949; #957; #957; #974;= do\u011fum vermek) canl\u0131n\u0131n b\u00fct\u00fcn \u00f6zelliklerinin eski ku\u015faktan yenisine nas\u0131l ge\u00e7ti\u011fini inceleyen bilim dal\u0131.
\n \u0130lk olarak Gregor Mendel’in yapt\u0131\u011f\u0131 \u00e7al\u0131\u015fmalarla bilim d\u00fcnyas\u0131nda tan\u0131nd\u0131\u011f\u0131 i\u00e7in Mendel geneti\u011fin babas\u0131 olarak da adland\u0131r\u0131l\u0131r.
\n Genetik bilimi 20.yy’\u0131n ilk yar\u0131s\u0131nda bilim insanlar\u0131 aras\u0131nda heyecan ve merak uyand\u0131rsa da as\u0131l etkisini ikinci elli y\u0131lda DNA’n\u0131n molek\u00fcler yap\u0131s\u0131n\u0131n ke\u015ffedilmesiyle g\u00f6stermi\u015ftir.
\n Bir anda bilimcilerin g\u00f6z bebe\u011fi haline gelen genetik 1980’li y\u0131llara gelindi\u011finde art\u0131k gelecek y\u00fczy\u0131l\u0131n bilimi olarak nitelendirmi\u015ftir. 1990’l\u0131 y\u0131llara gelindi\u011finde y\u0131llard\u0131r bilim insanlar\u0131n\u0131n hayallerini s\u00fcsleyen insan DNA dizinin haritas\u0131n\u0131n \u00e7\u0131kar\u0131lma fikri i\u00e7in ilk kez somut bir ad\u0131m at\u0131lm\u0131\u015ft\u0131r. Uuluslararas\u0131 bir konsorsiyumun ittifak\u0131yla \u0130nsan Genom projesi ba\u015flat\u0131lm\u0131\u015ft\u0131r. Tarihin en \u00f6nemli bilimsel geli\u015fmelerinden biri olarak kabul edilen s\u00f6z konusu #8216;harita ‘ sayesinde \u00f6l\u00fcmc\u00fcl hastal\u0131klar\u0131 \u00f6nceden te\u015fhis ederek \u00f6nleme, ki\u015fiye \u00f6zel ila\u00e7 ve tedavi y\u00f6ntemleri geli\u015ftirilebilme yolunda \u00e7ok \u00f6nemli katk\u0131lar sa\u011flanm\u0131\u015ft\u0131r.
\n Bug\u00fcn, genetik bilimi sayesinde bir\u00e7ok hastal\u0131\u011f\u0131n erken te\u015fhisi m\u00fcmk\u00fcn olabilmekte, bunun yan\u0131nda tedavi metotlar\u0131n\u0131n geli\u015fiminde olduk\u00e7a faydal\u0131 olmaktad\u0131r.
\n Tarih\u00e7esi
\n \u0130nsanlar\u0131n geli\u015fim s\u00fcresinde, ilk olarak do\u011fan \u00e7ocu\u011fun kime benzedi\u011fi sorusu, kal\u0131t\u0131m\u0131n ilk g\u00f6zlemleridir. \u00c7ocuklar\u0131n akrabalar\u0131na benzemesinin bir rastlant\u0131 olmad\u0131\u011f\u0131 \u00e7ok eski zamanlardan beri bilinmi\u015ftir. Bunun i\u00e7in, yak\u0131n akrabalar aras\u0131ndaki evlilikler yasaklanm\u0131\u015f, evcille\u015ftirilen hayvanlar\u0131n istenilen \u00f6zellikteki bireyleri \u00e7iftle\u015ftirilmi\u015ftir. Eski bir Babil yaz\u0131t\u0131nda be\u015f nesillik bir at \u015feceresinde yelebitkiler se\u00e7ilmi\u015f, yapay olarak tozla\u015fmalar yap\u0131lm\u0131\u015ft\u0131r. M\u0131s\u0131rl\u0131lar hurma polenleri ile notlar yazm\u0131\u015f, \u00c7inliler pirin\u00e719.yy’lar\u0131 bulmu\u015ftur. \u0130lk olarak yap\u0131lan kurgular Yunan filozoflardan gelmi\u015ftir. Bug\u00fcn komik olarak g\u00f6r\u00fclen fikirlerin, kal\u0131t\u0131m\u0131n ilk ana fikirleri olmas\u0131 nedeniyle b\u00fcy\u00fck \u00f6nemi vard\u0131r.<\/p>\n
Pitagor (Pytagoras) <\/p>\n
\u0130.\u00d6.500 y\u0131llar\u0131nda ya\u015fam\u0131\u015f olan d\u00fc\u015f\u00fcn\u00fcr, \u00e7ocuklar\u0131n babalar\u0131na benzerliklerini \u015f\u00f6yle a\u00e7\u0131klam\u0131\u015ft\u0131r; e\u015feysel \u00e7iftle\u015fme s\u0131ras\u0131nda v\u00fccudun de\u011fi\u015fik b\u00f6lgelerinden s\u00fcz\u00fclerek gelen \u0131slak buhar\u0131n e\u015feysel organlarda yo\u011funla\u015fmas\u0131yla tohum olu\u015fur ve di\u015fi e\u015fey organlar\u0131na iletilir. Bu buhar v\u00fccudun t\u00fcm par\u00e7alar\u0131n\u0131 yeniden olu\u015fturabilir. Ana ile benzerlik, embriyonun ana v\u00fccudu i\u00e7ersinde geli\u015fmesiyle anlat\u0131lm\u0131\u015ft\u0131r.<\/p>\n
Empedokles (Empedocles) <\/p>\n
Pitagor ile ayn\u0131 zamanlarda ya\u015fam\u0131\u015f, tohumun her iki atadan geldi\u011fine inanm\u0131\u015ft\u0131r. \u00c7iftle\u015fme s\u0131ras\u0131nda her iki atadan da gelen s\u0131v\u0131, tohum \u015feklinde organlaraembriyoyu olu\u015fturmaktayd\u0131. \u00c7ocuklar\u0131n ana ve babalar\u0131na benzemeleri, birbirine benzemeyen karde\u015flerin olu\u015fumu ise; v\u00fccudun her par\u00e7as\u0131ndan gelen tohuma katk\u0131 ayn\u0131 oranda olmad\u0131\u011f\u0131ndan, her yeni \u00e7iftle\u015fmede farkl\u0131 \u00e7ocuklar\u0131n olu\u015fmas\u0131 sa\u011flar, olarak a\u00e7\u0131klam\u0131\u015ft\u0131r.<\/p>\n
Aristo (Arisotle) <\/p>\n
\u0130.\u00d6.300 y\u0131llar\u0131nda ya\u015fam\u0131\u015f d\u00fc\u015f\u00fcn\u00fcr, bir\u00e7ok konuda oldu\u011fu gibi, kal\u0131t\u0131m \u00fczerine de fikirler ileri s\u00fcrm\u00fc\u015ft\u00fcr. D\u00fc\u015f\u00fcnceleri y\u00fczy\u0131llarca tart\u0131\u015f\u0131lmadan kabul g\u00f6rm\u00fc\u015ft\u00fcr. Erkek tohumunun kandan safla\u015ft\u0131r\u0131larak elde edildi\u011fine, kan\u0131n her organa ula\u015ft\u0131\u011f\u0131 i\u00e7in yeniden bu organlar\u0131 yapabilme g\u00fcc\u00fc oldu\u011funa inanm\u0131\u015ft\u0131r. Kad\u0131ndaki tohumun ayba\u015flar\u0131nda g\u00f6r\u00fclen adet kan\u0131 oldu\u011funu d\u00fc\u015f\u00fcnm\u00fc\u015f, ama erkekteki gibi tam olarak kan\u0131n safla\u015fmamas\u0131ndan dolay\u0131 kan \u015feklinde geldi\u011fini ileri s\u00fcrm\u00fc\u015ft\u00fcr. Aristo’ya g\u00f6re; \u00e7iftle\u015fme s\u0131ras\u0131nda tohumlar\u0131n ikisi birle\u015ferek embriyo haline gelip, \u00e7\u00f6kelmi\u015ftir. Bu fikir 2000 y\u0131l kadar kabul edilmi\u015f olup, g\u00fcn\u00fcm\u00fczde de kullan\u0131lan asil kanl\u0131 ve bozuk kanl\u0131 deyimlerinin buradan geldi\u011fine inan\u0131l\u0131r.
\n 1620 y\u0131l\u0131nda \u0130ngiliz ara\u015ft\u0131rmac\u0131 Harvey’in yapm\u0131\u015f baz\u0131 deneyler bu g\u00f6r\u00fc\u015f\u00fcn uzun y\u0131llar sonras\u0131nda sars\u0131lmas\u0131n\u0131 sa\u011flad\u0131. Geyikleri \u00e7iftle\u015ftirip, \u00f6ld\u00fcrerek rahimlerine bakt\u0131\u011f\u0131nda \u00e7\u00f6kelmi\u015f bir embriyo tasla\u011f\u0131 bulunmad\u0131\u011f\u0131n\u0131 g\u00f6rd\u00fc, fakat, \u00e7iftle\u015fme s\u0131ras\u0131nda olu\u015fan s\u00fcrt\u00fcnmeden do\u011fan m\u0131knat\u0131slanman\u0131n embriyo olu\u015fumuna yol a\u00e7t\u0131\u011f\u0131n\u0131 savundu. Mikroskobun ke\u015ffiyle bulunan e\u015fey h\u00fccreleri ile, erkekte sperm, di\u015fide yumurta h\u00fccresinin bulundu\u011fu anla\u015f\u0131ld\u0131. B\u00f6ylece e\u015fey h\u00fccrelerinin birle\u015fmesiyle meydana gelen h\u00fccreden yeni bir ya\u015fam\u0131n do\u011fdu\u011fu anla\u015f\u0131lm\u0131\u015f oldu.
\n Pangenezis ve Germ-Plazma kuramlar\u0131
\n Pangenezis
\n \u00c7o\u011fu insan, bulunan e\u015fey h\u00fccrelerine ra\u011fmen, hala v\u00fccut par\u00e7alar\u0131n\u0131n kal\u0131t\u0131ma etki etti\u011fine inan\u0131lmaktayd\u0131. Lamarck da bu g\u00f6r\u00fc\u015f\u00fc desteklemi\u015f, kazan\u0131lm\u0131\u015f \u00f6zelliklerin aktar\u0131ld\u0131\u011f\u0131 y\u00f6n\u00fcnde fikirler ileri s\u00fcrm\u00fc\u015ft\u00fcr. Bununla beraber Darwin de ilk zamanlar\u0131nda bu g\u00f6r\u00fc\u015f\u00fc desteklemi\u015f ve pangenezis denilen kuram\u0131 ileri s\u00fcrm\u00fc\u015ft\u00fcr. Pangenezisde her v\u00fccut h\u00fccresinin kana k\u00fc\u00e7\u00fck bir gemmula ya da pangenezis denilen yap\u0131lar verdi\u011fi, bunlar\u0131n \u00fcreme h\u00fccrelerinde topland\u0131\u011f\u0131 y\u00f6n\u00fcndeydi. Baz\u0131 ilkel canl\u0131larda g\u00f6r\u00fclen kuyruk kopmas\u0131 vs. gibi olaylarda gemmulalar\u0131n buralarda toplanarak onar\u0131m yapt\u0131\u011f\u0131n\u0131, baz\u0131 \u00e7ocuklar\u0131n b\u00fcy\u00fck aile bireylerine benzemelerinde gemmulalar\u0131n bazen embriyo olu\u015fumunda g\u00f6rev almadan do\u011frudan e\u015fey h\u00fccresine ge\u00e7erek bir sonraki d\u00f6lde etkisini g\u00f6stermesine ba\u011flam\u0131\u015ft\u0131r.
\n Germ-Plazma kuram\u0131
\n 19.yy’\u0131n sonlar\u0131na do\u011fru Weismann, pangenez kuram\u0131 \u00fczerine baz\u0131 \u00e7al\u0131\u015fmalar yaparak, birh\u00fccrelilerde protoplazman\u0131n s\u00fcrekli olmas\u0131na de\u011finmi\u015ftir. Birh\u00fccreliler b\u00f6l\u00fcnd\u00fcklerinde olu\u015fan yavrularda anadakinin ayn\u0131 protoplazma bulunur. Buna g\u00f6re, \u00e7okh\u00fccrelilerde de b\u00f6yle bir s\u00fcreklili\u011fin olabilece\u011fini d\u00fc\u015f\u00fcnerek, Germ-Plazma kuram\u0131n\u0131 ortaya atm\u0131\u015ft\u0131r. Buna g\u00f6re, y\u00fcksek canl\u0131lar, v\u00fccudu meydana getiren Somatoplazma k\u0131sm\u0131yla, \u00fcreme h\u00fccrelerini olu\u015fturan Germ Plazma’dan olu\u015fmu\u015ftur. Germ plazma embriyonik evrelerde di\u011fer dokulardan olu\u015fmu\u015f, fakat somatoplazma ile alakas\u0131 olmam\u0131\u015ft\u0131r g\u00f6r\u00fc\u015f\u00fcn\u00fc kabul etmi\u015ftir. Germ plazma, sperm ve yumurta olarak embriyoyu yapar, baz\u0131 h\u00fccreler embriyoda germ plazmay\u0131 olu\u015fturup, de\u011fi\u015fmeden kal\u0131rken, di\u011fer h\u00fccreler somatoplazma olarak farkl\u0131la\u015f\u0131r. Farelerin nesiller boyunca kuyruklar\u0131n\u0131 keserek, 23. yavrunun da kuyruklu do\u011fmas\u0131yla kazan\u0131lm\u0131\u015f \u00f6zelliklerin kal\u0131t\u0131lmad\u0131\u011f\u0131 y\u00f6n\u00fcnde bulgular elde etmi\u015f, b\u00f6ylece bu kuram ge\u00e7erlili\u011fini kaybetmi\u015ftir.
\n Hugo De Vries’in mutasyon kuram\u0131
\n Hugo De Vries, Darwin’in kuramlar\u0131n\u0131 benimsemi\u015f, fakat pargenezisi kabul etmemi\u015f, t\u00fcrler aras\u0131ndaki b\u00fcy\u00fck varyasyonlar\u0131n temelini bulmaya e\u011filmi\u015ftir. Laleler ile yapt\u0131\u011f\u0131 g\u00f6zlemlerinde aniden ortaya \u00e7\u0131kan de\u011fi\u015fik t\u00fcrlerin nedenini mutasyonlare\u015fek\u00e7i\u00e7ekleri ile saf varyeteler elde etmi\u015ftir. \u00c7al\u0131\u015fmalar\u0131n\u0131 yay\u0131mlayaca\u011f\u0131 zaman, Mendel’in bezelyede ayn\u0131 \u015feyleri farketmi\u015f oldu\u011funu g\u00f6rd\u00fc, bulu\u015funu Mendel ile birlikte 1900 y\u0131l\u0131nda yay\u0131mlayarak, kal\u0131tsal birimlerin de\u011fi\u015febilece\u011fine ait g\u00f6r\u00fc\u015f\u00fcn\u00fc kabul ettirmi\u015ftir.
\n Mendel ve ilk genetik deneyi
\n Avusturyal\u0131 botanik\u00e7i ve papaz Gregor Mendel, g\u00fcn\u00fcm\u00fcz\u00fcn pop\u00fcler bilimi olan genetik biliminin, babas\u0131 olarak kabul edilir. 1856 y\u0131l\u0131ndan itibaren \u00e7e\u015fitli bezelyePisum sativum) varyetelerine ait tohumlar\u0131 toplamaya ve onlar\u0131 manast\u0131r bah\u00e7esinde yeti\u015ftirerek aralar\u0131ndaki farklar\u0131 incelemeye ba\u015flam\u0131\u015ft\u0131r. 10 y\u0131ll\u0131k \u00e7al\u0131\u015fmas\u0131n\u0131n \u00f6nemli bulgular\u0131n\u0131 Versuche \u00dcber Pflanzenhybriden (Bitki melezleri ile \u00e7al\u0131\u015fmalar) adl\u0131 \u00fcnl\u00fc inceleme yaz\u0131s\u0131yla yay\u0131mlam\u0131\u015ft\u0131r.
\n O tarihlerde DNA, kromozom, mayoz b\u00f6l\u00fcnme gibi kavramlar hen\u00fcz g\u00fcn \u0131\u015f\u0131\u011f\u0131na \u00e7\u0131kmad\u0131\u011f\u0131 halde Mendel ‘in sadece Fenotipik (g\u00f6zlenebilen) karakter ayr\u0131l\u0131klar\u0131na g\u00f6re de\u011ferlendirmeleri, son derece do\u011fru bi\u00e7imdedir.
\n \u00c7al\u0131\u015fmalar\u0131 ve ke\u015fifleri ya\u015fad\u0131\u011f\u0131 d\u00f6nem i\u00e7inde hi\u00e7bir ilgi uyand\u0131rmam\u0131\u015f ve kimse \u00f6nemini fark etmemi\u015ftir. \u00d6l\u00fcm\u00fcnden onalt\u0131 y\u0131l sonra Hollanda ‘da Hugo De Vries, Almanya ‘da Correns ve Avusturya ‘da E. Von Tschermak adl\u0131 \u00fc\u00e7 biyolog, \u00e7e\u015fitli bitki t\u00fcrlerinde, birbirlerinden habersiz yapt\u0131klar\u0131 ara\u015ft\u0131rmalarda, Mendel yasalar\u0131n\u0131n ge\u00e7erlili\u011fini g\u00f6sterdiler. Mendel yasalar\u0131 ad\u0131 alt\u0131nda t\u00fcm sonu\u00e7lar\u0131 toparlad\u0131lar.
\n Mendel ‘in, \u00e7aprazlama deneyleri i\u00e7in \u00f6zellikle bezelye bitkisini tercih etmesinin, nedenleri vard\u0131. Tozla\u015fman\u0131n kontroll\u00fc bir \u015fekilde ger\u00e7ekle\u015ftirilmesi ve de kendi kendine tozla\u015fman\u0131n engellenebilmesi, basit y\u00f6ntemler uygulanarak sa\u011flanabiliyordu. Kal\u0131t\u0131m\u0131n, biraz karma\u015f\u0131k ilkelerini \u00e7\u00f6zebilmek i\u00e7in fenotipik karakterleri zengin olan bitkiler se\u00e7ilir. \u00d6zellikle bezelye bitkisinin 7 farkl\u0131 fenotipik karakteri olmas\u0131 \u00e7al\u0131\u015fmalara kolayl\u0131k getirmi\u015ftir. Tohumun bi\u00e7imi (d\u00fczg\u00fcn-buru\u015fuk), tohumun rengi (sar\u0131-ye\u015fil), meyve kabu\u011fu bi\u00e7imi (\u015fi\u015fkin-dar), meyve kabu\u011fu rengi (sar\u0131-ye\u015fil), g\u00f6vde boyu (uzun-k\u0131sa) gibi \u00f6zellikler fenotipik karakterlere \u00f6rnek g\u00f6sterilebilir.
\n \u00c7aprazlama; genetikte, hayvanlarda \u00e7iftle\u015ftirme, bitkilerde tozla\u015ft\u0131rma \u015feklinde organizmalar aras\u0131nda yap\u0131lan kontroll\u00fc d\u00f6llenme \u00e7al\u0131\u015fmalar\u0131d\u0131r. As\u0131rlar boyunca, kal\u0131t\u0131m\u0131n, \u00e7ocuklarda, anne ve baban\u0131n karakterlerinin bir kar\u0131\u015f\u0131m\u0131 olarak ortaya \u00e7\u0131kt\u0131\u011f\u0131na inan\u0131lm\u0131\u015f, Mendel bu fikri reddederek kendi ad\u0131yla belirlenen yasalar\u0131 belirlemi\u015fti. Mendel bir karaktere ait fenotiplerden birinin di\u011ferinden daha bask\u0131n oldu\u011funu, \u00e7e\u015fitli varyetedeki bezelye tohumlar\u0131 aras\u0131nda, kar\u015f\u0131l\u0131kl\u0131 \u00e7aprazlamalar yaparak g\u00f6stermi\u015ftir. Sar\u0131 ve ye\u015fil bezelye bitkilerini di\u015fi ve erkek olarak ayr\u0131 ayr\u0131 kulland\u0131. \u00c7aprazlama sonucundaki ilk d\u00f6l\u00fcn (F1 d\u00f6l\u00fc) ana ve babadan sadece birine benzedi\u011fi g\u00f6r\u00fcld\u00fc. Bu ke\u015fif karakterlerin kar\u0131\u015f\u0131m esas\u0131na g\u00f6re da\u011f\u0131l\u0131m g\u00f6r\u00fc\u015f\u00fcn\u00fc y\u0131km\u0131\u015ft\u0131r.
\n K\u0131sa Notlar
\n V\u00fccut h\u00fccrelerimizin kromozom say\u0131s\u0131 2n dir. Gametlerde (e\u015fey h\u00fccreleri) ise bu say\u0131 mayoz b\u00f6l\u00fcnme gere\u011fi yar\u0131ya d\u00fc\u015fer ve n olur. Anne ve babadan sperm (n) ve yumurta (n) h\u00fccreleri (e\u015fey h\u00fccreleri) ile ta\u015f\u0131nan kromozomlar birle\u015ferek 2n say\u0131daki zigotkromozom say\u0131s\u0131 mayoz ile korunmu\u015f olur. Zigotun ergin bireyi olu\u015fturmas\u0131na dek s\u00fcrd\u00fcrd\u00fc\u011f\u00fc h\u00fccre b\u00f6l\u00fcnme program\u0131 art\u0131k mitozdur. Bu b\u00f6l\u00fcnme tipinde kromozom say\u0131s\u0131 hep sabittir. Bitkilerde de ayn\u0131 kural ge\u00e7erlidir. E\u015fey h\u00fccreleri, polen ve embriyo kesesindeki yumurtad\u0131r.
\n Kal\u0131tsal molek\u00fclde (DNA) bulunan ve canl\u0131n\u0131n karakterlerinin belirlenmesinde rol oynayan kal\u0131tsal birimlere gen ad\u0131 verilir. Bir genin DNA molek\u00fcl\u00fcnde kaplad\u0131\u011f\u0131 fiziksel alan i\u00e7in lokus deyimi kullan\u0131l\u0131r. \u00d6rne\u011fin bezelyedeki tohumun, rengini belirleyen genin kaplad\u0131\u011f\u0131 alan bir lokustur. Bir lokusta mevcut renk bilgilerinin her birine de allel ad\u0131 verilir. Sar\u0131 renk bir allel, ye\u015fil renk bir allel. Daha genel bir tarifleme ile bir genin de\u011fi\u015fik bi\u00e7imlerine allel ad\u0131 verilir.
\n Mendel, fenotipik karakterlerin \u00e7aprazlanmas\u0131 s\u0131ras\u0131nda alleleri, alfabenin bir harfi ile simgelemi\u015ftir. Dominant (bask\u0131n) karakterleri b\u00fcy\u00fck harf, resesif (\u00e7ekinik) karakterleri de k\u00fc\u00e7\u00fck harfle g\u00f6stermi\u015ftir. \u00c7aprazlamadaki saf soylara ait bitkiler i\u00e7in, ana-baba (parental) ku\u015fa\u011f\u0131 anlam\u0131nda P simgesi, bunlar\u0131n \u00e7aprazlanmas\u0131ndan meydana gelen birinci ku\u015fak i\u00e7in F1 simgesi kullan\u0131lm\u0131\u015ft\u0131r. \u00c7aprazlaman\u0131n devam\u0131nda meydana gelen d\u00f6ller F2, F3 vb. simgeler kullan\u0131lm\u0131\u015ft\u0131r.
\n Saf soylara (ar\u0131 \u0131rk) ait sar\u0131 bezelye tohumlar\u0131 SS, ye\u015fil bezelye tohumlar\u0131 ise ss olarak g\u00f6sterilir. \u00c7ift harf kullan\u0131lmas\u0131n\u0131n nedeni bir lokusta iki karakterin (allel) mevcut olmas\u0131d\u0131r. Bu allellerden birisi anneden di\u011feri babadan gelmi\u015ftir. Sar\u0131 allel ye\u015fil allele dominantt\u0131r bu nedenle Ss allel durumunda g\u00f6zlenecek fenotipik karakter sar\u0131 olacakt\u0131r. ba\u015f\u0131n\u0131n de\u011fi\u015fimi g\u00f6sterilmi\u015ftir. Tohum se\u00e7iminde en iyi \u0131rklar\u0131n\u0131n daha kaliteli olmas\u0131 i\u00e7in tozla\u015fmalar yapm\u0131\u015flard\u0131r. Bununla beraber, geneti\u011fin bilimsel olarak a\u00e7\u0131klanmas\u0131 ancak, toplanmakta, birle\u015fmelerinde ise olarak a\u00e7\u0131klam\u0131\u015ft\u0131r. Daha sonralar\u0131 yapt\u0131\u011f\u0131 \u00e7al\u0131\u015fmalarda yeti\u015ftirdi\u011fi ( h\u00fccresini olu\u015fturur. B\u00f6ylece
\n Mendel ‘in 1. yasas\u0131:
\n Allellerin ayr\u0131\u015f\u0131m prensibi = Ba\u011f\u0131ms\u0131z ayr\u0131\u015f\u0131m prensibi P: SS (anne) X ss (baba) kromozom say\u0131s\u0131:2n Bu karakterler \u00e7aprazlan\u0131r Muhtemel aleller: G: S (anneden) ve s (babadan) kromozom say\u0131s\u0131: n F1: Ss \u00c7aprazlama sonucu olu\u015fan karakter sar\u0131 renk tohumdur.
\n Birbirlerinden belli bir karakterin farkl\u0131 iki \u00e7e\u015fidiyle ay\u0131rt edilen (iki allel) iki saf soyun aralar\u0131nda \u00e7aprazlanmas\u0131 sonucu F1 d\u00f6l\u00fcnde, ana ve babadan yaln\u0131z birine benzeyen homojen bireyler ortaya \u00e7\u0131kar.
\n Mendel bu bulgulara g\u00f6re \u015fu a\u00e7\u0131klamalar\u0131 yapm\u0131\u015ft\u0131r:
\n Belli bir karakteri belirleyen kal\u0131tsal belirleyiciler vard\u0131r (g\u00fcn\u00fcm\u00fczde gen ad\u0131 verilen birimler).
\n Her ergin bireyin h\u00fccrelerinde bir karaktere ait 2 belirleyici (2 allel) bulunmaktad\u0131r. F1 de bunlardan biri dominant di\u011feri resesiftir.
\n Kal\u0131tsal belirleyiciler gamet h\u00fccreleri arac\u0131l\u0131\u011f\u0131 ile d\u00f6lden d\u00f6le nakledilir. E\u015fey h\u00fccreleri olu\u015fumu s\u0131ras\u0131nda, ayr\u0131lan allellerin taksimi tamamen ba\u011f\u0131ms\u0131z ve e\u015fit \u015fekilde ger\u00e7ekle\u015fir. \u00d6rne\u011fin Ss allel \u00e7ifti ta\u015f\u0131yan bir annenin allelleri S ve s #8216;dir. Olu\u015facak e\u015fey h\u00fccresine, bu karakter belirliyicisinin S alleli iletilir, di\u011fer h\u00fccreye de s alleli iletir. Her e\u015fey h\u00fccresi her bir karaktere ait sadece bir allel ta\u015f\u0131yabilir. \u0130\u015fte bu Mendel ‘in birinci yasas\u0131n\u0131n temelidir.
\n Mendel ‘in 2. yasas\u0131:
\n Bireylerin ilk h\u00fccresini (zigotu) olu\u015fturmak \u00fczere e\u015fey h\u00fccrelerinin birle\u015fmesi tamamen rastlant\u0131ya ba\u011fl\u0131d\u0131r. F1 d\u00f6llerin kendi aralar\u0131nda \u00e7aprazlanmas\u0131yla elde edilen d\u00f6l F2 d\u00f6l\u00fcd\u00fcr. Belli bir karakterin her iki \u00e7e\u015fidini g\u00f6steren bireyler her zaman belirli ve sabit oranda \u00e7\u0131karlar.
\n P: Ss X Ss
\n F1 d\u00f6ller kendi aralar\u0131nda \u00e7aprazlan\u0131r.
\n G: S s S s
\n E\u015fey h\u00fccrelerine taksim edilen muhtemel alleler.
\n F2: G S s <\/p>\n
S SS Ss
\n s Ss ss <\/p>\n
%25 SS
\n %50 Ss
\n %25 ss
\n Oranlar\u0131 hi\u00e7 bir zaman de\u011fi\u015fmez — 3:1
\n Sar\u0131 renkli tohumlar\u0131n ye\u015fil renklilere oran\u0131d\u0131r.<\/p>\n
Geneti\u011fin dallar\u0131<\/p>\n
Genel (Klasik) Genetik
\n Davran\u0131\u015f Geneti\u011fi
\n Molek\u00fcler Genetik
\n Populasyon Geneti\u011fi
\n Ekoloji Geneti\u011fi
\n Genom
\n Ayr\u0131ca konu olarak;<\/p>\n
Mendel
\n Genler ve Alleller
\n Monohibrit \u00e7aprazlama
\n Dihibrit \u00e7aprazlama
\n Genetik olas\u0131l\u0131k
\n Yar\u0131 bask\u0131nl\u0131k
\n Genotip
\n E\u015fey saptanmas\u0131
\n Genler aras\u0131ndaki il\u015fikiler
\n Poligenik kal\u0131t\u0131m
\n Molek\u00fcler genetik
\n Genetik Bilimi’nin i\u00e7eri\u011fini \u00f6zetler.<\/p>\n","protected":false},"excerpt":{"rendered":"
Genetik, (Yunanca’dan genno #947; #949; #957; #957; #974;= do\u011fum vermek) canl\u0131n\u0131n b\u00fct\u00fcn \u00f6zelliklerinin eski ku\u015faktan yenisine nas\u0131l ge\u00e7ti\u011fini inceleyen bilim dal\u0131. \u0130lk olarak Gregor Mendel’in yapt\u0131\u011f\u0131 \u00e7al\u0131\u015fmalarla bilim d\u00fcnyas\u0131nda tan\u0131nd\u0131\u011f\u0131 i\u00e7in Mendel geneti\u011fin babas\u0131 olarak da adland\u0131r\u0131l\u0131r. Genetik bilimi 20.yy’\u0131n ilk yar\u0131s\u0131nda bilim insanlar\u0131 aras\u0131nda heyecan ve merak uyand\u0131rsa da as\u0131l etkisini ikinci elli y\u0131lda …<\/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":[8307,2132,8306,8305,2577,8300,8302,8309,8301,2470,2601,8308,8303,8304],"class_list":["post-3640","post","type-post","status-publish","format-standard","hentry","category-fen-ve-teknoloji-odevleri","category-odevler","tag-arisotle","tag-aristo","tag-empedocles","tag-empedokles","tag-fenotip","tag-genetik-aciklama","tag-insan-genom-projesi","tag-kalitsal","tag-konsorsiyum","tag-kromozom","tag-mendel","tag-pangenezis","tag-pitagor","tag-pytagoras"],"_links":{"self":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts\/3640","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=3640"}],"version-history":[{"count":0,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts\/3640\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/media?parent=3640"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/categories?post=3640"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/tags?post=3640"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}