{"id":25784,"date":"2018-05-21T12:14:41","date_gmt":"2018-05-21T09:14:41","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=25784"},"modified":"2018-05-21T12:14:41","modified_gmt":"2018-05-21T09:14:41","slug":"gen-sayilari-ve-dna-buyuklukleri-evrimi-curutuyor-mu","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2018\/05\/21\/gen-sayilari-ve-dna-buyuklukleri-evrimi-curutuyor-mu","title":{"rendered":"Gen say\u0131lar\u0131 ve DNA b\u00fcy\u00fckl\u00fckleri evrimi \u00e7\u00fcr\u00fct\u00fcyor mu?"},"content":{"rendered":"

Yarat\u0131l\u0131\u015f\u00e7\u0131lar\u0131n iddias\u0131: <\/strong>Gen say\u0131lar\u0131 ve DNA b\u00fcy\u00fckl\u00fckleri evrimi \u00e7\u00fcr\u00fct\u00fcyor<\/strong><\/p>\n

Bilimin yan\u0131t\u0131: Ne gen say\u0131s\u0131 ne de DNA b\u00fcy\u00fckl\u00fckleri evrimi \u00e7\u00fcr\u00fct\u00fcr<\/strong><\/p>\n

\u00a0<\/strong>\u201cNe gen say\u0131lar\u0131 ne de DNA b\u00fcy\u00fckl\u00fckleri, evrimcilerin \u00f6ne s\u00fcrd\u00fc\u011f\u00fc gibi bir \u201cevrim zinciri\u201d g\u00f6stermemektedir.\u201d (www.harunyahya.org\/evrim\/darwin_dna_bilseydi\/darwin_dna_bilseydi_11.html).<\/p>\n

Prof. Dr. Asl\u0131han Tolun – N\u0131vart Ta\u015f\u00e7\u0131 – Mehmet Do\u011fan
\n<\/strong>Bo\u011fazi\u00e7i \u00dcniversitesi Molek\u00fcler Biyoloji ve Genetik B\u00f6l\u00fcm\u00fc<\/p>\n

Biliminsanlar\u0131 savlar\u0131n\u0131 insan\u0131n daha karma\u015f\u0131k bir canl\u0131 oldu\u011fu, dolay\u0131s\u0131yla gen say\u0131lar\u0131n\u0131n da daha fazla oldu\u011fu mant\u0131\u011f\u0131 \u00fczerine kurmazlar. Gen say\u0131s\u0131 t\u00fcr i\u00e7inde korunmakla beraber, t\u00fcrler aras\u0131nda belli bir aral\u0131kta de\u011fi\u015fkenlik g\u00f6sterir. \u00d6rne\u011fin Mycoplasma genitalium<\/em> t\u00fcr\u00fc bakteride 470, maya h\u00fccresinde 6.000, bir meyvesine\u011fi t\u00fcr\u00fc olan Drosophila melanogaster<\/em>\u2019de 13.000, Arabidopsis thaliana<\/em> bitkisinde 25.000 gen bulunur. \u0130nsan Genom Projesi\u2019nin tamamlanmas\u0131yla beraber, insanlardaki gen say\u0131s\u0131n\u0131n yakla\u015f\u0131k 30.000 oldu\u011fu saptanm\u0131\u015ft\u0131r. Genler, v\u00fccuttaki her t\u00fcrl\u00fc molek\u00fcler eylemin ve yap\u0131sal olu\u015fumlar\u0131n \u015fifresini i\u00e7ermelerine ra\u011fmen, bunlardan sentezlenen molek\u00fcllerin say\u0131s\u0131 gen say\u0131s\u0131n\u0131n \u00e7ok daha \u00fczerindedir. Bunun anlam\u0131, her genin tek bir protein -veya RNA molek\u00fcl\u00fcne- kar\u015f\u0131l\u0131k gelmedi\u011fidir. Ayn\u0131 genden farkl\u0131 proteinlerin ya da RNA\u2019lar\u0131n \u00fcretilmesi i\u00e7in \u00e7e\u015fitli genetik mekanizmalar\u0131n varl\u0131\u011f\u0131 bilinmektedir. Bunun d\u0131\u015f\u0131nda \u015fifresi de\u011fi\u015fmese de, bir genden farkl\u0131 dokularda farkl\u0131 proteinler sentezlenebilir. \u00d6rne\u011fin distrofin geni, kasta, beyin dokusunda ve retinada farkl\u0131 proteinler \u00fcretir. Protein sentezindeki bu \u00e7e\u015fitlilik, h\u00fccrenin d\u0131\u015f etkilere verece\u011fi cevapta ya da geli\u015fim takvimine uyma \u00e7abas\u0131nda yeterli karma\u015f\u0131kl\u0131\u011fa ula\u015fmas\u0131n\u0131 sa\u011flar. Ayr\u0131ca genlerdeki \u00fcretim sadece nitelik d\u00fczeyinde de\u011fil, zamansal ve nicel a\u00e7\u0131lardan da farkl\u0131l\u0131k g\u00f6sterebilir. Yani bir genin \u00fcretimindeki tek kritik nokta, dolay\u0131s\u0131yla biyolojik karma\u015f\u0131kl\u0131\u011f\u0131 belirleyen tek etken sadece genin \u00fcr\u00fcn\u00fc de\u011fil, ayn\u0131 zamanda \u00fcretim zaman\u0131 ve h\u0131z\u0131d\u0131r. Sonu\u00e7ta h\u00fccrelerin t\u00fcm\u00fcnde ayn\u0131 DNA olmas\u0131, h\u00fccre farkl\u0131la\u015fmas\u0131n\u0131 engellemez. \u00d6nemli olan genomun i\u00e7inde bulundu\u011fu h\u00fccresel dinamiklerin DNA \u00fczerindeki belirleyicili\u011fidir.<\/p>\n

Yap\u0131lan \u00e7al\u0131\u015fmalar, fizyolojik olarak daha basit olan arkea ve bakteri gibi canl\u0131lar\u0131n genom boylar\u0131n\u0131n belirli bir minimum de\u011ferde olmas\u0131 gerekti\u011fini g\u00f6stermi\u015ftir. Bu organizmalarda \u00e7\u00f6p DNA oran\u0131n\u0131n \u00e7ok d\u00fc\u015f\u00fck olmas\u0131, genom uzunlu\u011fu ile gen say\u0131lar\u0131 aras\u0131nda belli bir do\u011frusall\u0131k yaratmaktad\u0131r. Minimum genom boyu ilkesi ayn\u0131 \u015fekilde, y\u00fcksek \u00f6karyotlar i\u00e7in de ge\u00e7erlidir. Fakat \u00f6karyotlarda genom boyu ve gen say\u0131s\u0131 aras\u0131ndaki ili\u015fki kaybolmu\u015f, yerini do\u011frudan genlerin kendi alt birimlerinin (\u015fifreleyici eksonlar, sentez zaman\u0131n\u0131 ve miktar\u0131n\u0131 ayarlayan tetikleyici veya yava\u015flat\u0131c\u0131 diziler gibi) say\u0131lar\u0131n\u0131 art\u0131rmas\u0131, yani genlerin karma\u015f\u0131kla\u015fmas\u0131 s\u00fcreci alm\u0131\u015ft\u0131r. Yani gen say\u0131s\u0131na bakarak, bir organizman\u0131n karma\u015f\u0131kl\u0131\u011f\u0131 hakk\u0131nda ancak \u00fcst\u00fcnk\u00f6r\u00fc bir tahminde bulunabiliriz. Y\u00fcksek \u00f6karyotlardan bir canl\u0131n\u0131n gen say\u0131s\u0131n\u0131n insandaki gen say\u0131s\u0131ndan fazla olmas\u0131, bu organizman\u0131n insandan daha karma\u015f\u0131k oldu\u011fu anlam\u0131na gelmez, fakat kesinlikle bakterilerden daha karma\u015f\u0131k oldu\u011funu s\u00f6yleyebilir. \u00d6karyotlar\u0131n kendi aralar\u0131ndaki niteliksel kar\u015f\u0131la\u015ft\u0131rmalar ise genom boyu veya gen say\u0131s\u0131 \u00fczerinden de\u011fil, do\u011frudan genlerin yap\u0131s\u0131, etkile\u015fimleri ve \u00fcr\u00fcnleri olan proteinlerin \u00f6zellikleri arac\u0131l\u0131\u011f\u0131yla yap\u0131lmaktad\u0131r.<\/p>\n

Sonu\u00e7ta do\u011fan\u0131n hem molek\u00fcler hem makro d\u00fczeyde karma\u015f\u0131kl\u0131k \u00fcretmek i\u00e7in binlerce mekanizmas\u0131 vard\u0131r. Bu mekanizmalardan hi\u00e7biri, A \u00f6zelli\u011fi sadece B de\u011fi\u015fkenine ba\u011fl\u0131d\u0131r gibi basit, tek boyutlu ve her an y\u0131k\u0131lma riskine sahip bir ba\u011f\u0131nt\u0131 i\u00e7ermez ve i\u00e7ermemelidir. Bilimin, organizma karma\u015f\u0131kl\u0131\u011f\u0131n\u0131 sadece gen say\u0131s\u0131na ba\u011flama basitli\u011fine d\u00fc\u015fece\u011fini varsaymak \u00f6nyarg\u0131l\u0131 bir yakla\u015f\u0131md\u0131r.<\/p>\n

Kaynak<\/strong><\/p>\n

1) Lewin, B., Genes VIII<\/em>, Perason Education, Inc., New Jersey,2004.<\/p>\n","protected":false},"excerpt":{"rendered":"

Yarat\u0131l\u0131\u015f\u00e7\u0131lar\u0131n iddias\u0131: Gen say\u0131lar\u0131 ve DNA b\u00fcy\u00fckl\u00fckleri evrimi \u00e7\u00fcr\u00fct\u00fcyor Bilimin yan\u0131t\u0131: Ne gen say\u0131s\u0131 ne de DNA b\u00fcy\u00fckl\u00fckleri evrimi \u00e7\u00fcr\u00fct\u00fcr \u00a0\u201cNe gen say\u0131lar\u0131 ne de DNA b\u00fcy\u00fckl\u00fckleri, evrimcilerin \u00f6ne s\u00fcrd\u00fc\u011f\u00fc gibi bir \u201cevrim zinciri\u201d g\u00f6stermemektedir.\u201d (www.harunyahya.org\/evrim\/darwin_dna_bilseydi\/darwin_dna_bilseydi_11.html). Prof. Dr. Asl\u0131han Tolun – N\u0131vart Ta\u015f\u00e7\u0131 – Mehmet Do\u011fan Bo\u011fazi\u00e7i \u00dcniversitesi Molek\u00fcler Biyoloji ve Genetik B\u00f6l\u00fcm\u00fc Biliminsanlar\u0131 savlar\u0131n\u0131 […]<\/p>\n","protected":false},"author":184,"featured_media":25785,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[19,21,231],"tags":[272,431,773,2055],"class_list":["post-25784","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bilim-gundemi","category-biyoloji","category-molekuler-biyoloji-ve-genetik","tag-dna","tag-gen","tag-genom","tag-rna"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t