B\u00fct\u00fcn d\u00f6llerde kromozom say\u0131s\u0131n\u0131n de\u011fi\u015fmez kalabilmesi i\u00e7in (sperm ve yumurtan\u0131n birle\u015fmesinden kromozom say\u0131s\u0131 iki kat\u0131na \u00e7\u0131kaca\u011f\u0131ndan dolay\u0131) farkl\u0131 bir h\u00fccre b\u00f6l\u00fcnmesi geli\u015fmi\u015ftir. Mayoz b\u00f6l\u00fcnme ismini alan bu tip b\u00f6l\u00fcnmede, kromozom say\u0131s\u0131 yar\u0131ya indirgenir. Mayoz b\u00f6l\u00fcnmenin sonunda meydana gelen gametler di\u011fer v\u00fccut h\u00fccrelerinin aksine n say\u0131da kromozom ta\u015f\u0131r (baz\u0131 bitkilerde ve bir h\u00fccrelilerde bireyin kendisi ya\u015fant\u0131s\u0131 boyunca haploid kromozomlu oldu\u011fundan mayoz b\u00f6l\u00fcnmeye gerek kalmaz). Normal olarak soma h\u00fccrelerinde 2n kromozomlardan homolog olanlar, boyuna, sinaps dedi\u011fimiz aral\u0131klarla birbirinin yak\u0131n\u0131nda uzan\u0131rlar. Bu homolog kromozomlar\u0131n her biri ayr\u0131 bir kutba giderek, yaln\u0131z bir tanesinin bir gamete verilmesi sa\u011flan\u0131r. Homolog kromozomlar ayn\u0131 b\u00fcy\u00fckl\u00fc\u011fe ve \u015fekle, keza benzer kal\u0131tsal fakt\u00f6rlere sahiptir. Gerek yumurta gerekse sperm olu\u015fumu son iki h\u00fccre b\u00f6l\u00fcnmesine kadar ayn\u0131 kurallara g\u00f6re y\u00fcr\u00fct\u00fcl\u00fcr. Daha sonra spermatogenezis (sperm olu\u015fumu) ve oogenesiz (yumurta olu\u015fumu) farkl\u0131 \u015fekilde meydana gelir.
\n Mayozda da mitoz gibi profaz, metafaz, anafaz ve telofaz diye d\u00f6rt evre vard\u0131r. Bu evreler arada interfaz olmaks\u0131z\u0131n pe\u015f pe\u015fe iki kez ger\u00e7ekle\u015fir ve sonu\u00e7ta d\u00f6rt yavru h\u00fccre meydana gelir. Mayoz b\u00f6l\u00fcnme ile mitoz b\u00f6l\u00fcnme aras\u0131ndaki en b\u00fcy\u00fck farka profazda rastlan\u0131r.
\n \u0130nterfaz
\n B\u00f6l\u00fcnmeye haz\u0131rl\u0131k evresidir. Mitozdaki interfaza benzemekle birlikte h\u00fccrelerin mitozdaki gibi b\u00fcy\u00fckl\u00fcklerinin ve hacimlerinin artmas\u0131 ger\u00e7ekle\u015fmez.
\n Profaz-I
\n Kromozomlar k\u0131sal\u0131p kal\u0131nla\u015fmaya ba\u015flarken, anadan ve babadan gelen homolog kromozomlar sinaps halinde ya yan yana parelel uzan\u0131rlar ya da birbirinin \u00fczerine k\u0131vr\u0131l\u0131rlar. K\u0131salma sonucunda kromozomlar mitozdaki gibi g\u00f6r\u00fclmeye ba\u015flar. Her kromozom iki kromatitten yap\u0131ld\u0131\u011f\u0131ndan, homolog kromozomlar d\u00f6rtl\u00fc demetler halinde g\u00f6r\u00fcl\u00fcr, bu g\u00f6r\u00fcn\u00fc\u015fe tetrat denir. Canl\u0131n\u0131n v\u00fccudunda homolog kromozom kadar tetrata rastlan\u0131l\u0131r (insanda 23 tane). Kromozomlar\u0131n sentromerleri ayr\u0131lmam\u0131\u015ft\u0131r. 4 kromatid i\u00e7in iki sentromer vard\u0131r.
\n Ayr\u0131ca mitozdan farkl\u0131 olarak bu evrede tetratlar aras\u0131nda par\u00e7a de\u011fi\u015fimi ger\u00e7ekle\u015fir. Krossing-over denilen bu par\u00e7a de\u011fi\u015fimi t\u00fcr i\u00e7inde \u00e7e\u015fitlili\u011fi sa\u011flar. Bu evrenin sonunda \u00e7ekirdek zar\u0131 par\u00e7alanarak kaybolur.
\n Metafaz-I
\n \u00c7ekirdek zar\u0131n\u0131n par\u00e7alanmas\u0131 sona ermi\u015f, sentrozomlar kutupulara \u00e7ekilmi\u015f ve i\u011f iplikleri ortaya \u00e7\u0131km\u0131\u015ft\u0131r. Sentromerleri \u00e7ift olan tetratlar ekvatoral d\u00fczlem \u00fczerine dizilir.
\n Anafaz-I
\n Bu evrede tetratlar ikiye ayr\u0131larak kutuplara giderler. Ana ve babadan gelen kromozomlar rasgele olarak birbirlerinden ayr\u0131l\u0131rlar (\u00f6zelliklerimizin baz\u0131lar\u0131n\u0131n anadan baz\u0131lar\u0131n\u0131n babadan ge\u00e7mesinin nedeni). Bu evrede kromozom say\u0131s\u0131 indirgendi\u011finden kutuplara ta\u015f\u0131nan yani o\u011ful h\u00fccrelere ge\u00e7ecek olan kromozom say\u0131s\u0131 v\u00fccut h\u00fccrelerinin kromozom say\u0131s\u0131n\u0131n yar\u0131s\u0131 kadard\u0131r.
\n Telofaz-I
\n H\u00fccrenin iki kutbunda bulunan kromozomlar uzay\u0131p incelmeye ba\u015flar. Etraflar\u0131nda \u00e7ekirdek zar\u0131 olu\u015fur. Sitoplazman\u0131n bo\u011fumlanmas\u0131yla da haploid say\u0131da kromozoma sahip iki yavru h\u00fccre olu\u015fur.
\n Buraya kadar ge\u00e7en olaylar mayoz-I olarak adland\u0131r\u0131l\u0131r. Bundan sonra mitozdakinin aksine arada interfaz evresi olmaks\u0131z\u0131n profaz-II’nin ba\u015flamas\u0131yla mayoz-II ba\u015flar. Mayoz-II mitoz b\u00f6l\u00fcnmenin hemen hemen ayn\u0131s\u0131d\u0131r. H\u00fccrelerdeki haploid kromozom say\u0131s\u0131 korunarak profaz-II, metafaz-II, anafaz-II ve telofaz-II ger\u00e7ekle\u015ferek mayoz b\u00f6l\u00fcnmenin sonunda n kromozom say\u0131s\u0131na sahip 4 yavru h\u00fccre meydana gelir.<\/p>\n","protected":false},"excerpt":{"rendered":"
B\u00fct\u00fcn d\u00f6llerde kromozom say\u0131s\u0131n\u0131n de\u011fi\u015fmez kalabilmesi i\u00e7in (sperm ve yumurtan\u0131n birle\u015fmesinden kromozom say\u0131s\u0131 iki kat\u0131na \u00e7\u0131kaca\u011f\u0131ndan dolay\u0131) farkl\u0131 bir h\u00fccre b\u00f6l\u00fcnmesi geli\u015fmi\u015ftir. Mayoz b\u00f6l\u00fcnme ismini alan bu tip b\u00f6l\u00fcnmede, kromozom say\u0131s\u0131 yar\u0131ya indirgenir. Mayoz b\u00f6l\u00fcnmenin sonunda meydana gelen gametler di\u011fer v\u00fccut h\u00fccrelerinin aksine n say\u0131da kromozom ta\u015f\u0131r (baz\u0131 bitkilerde ve bir h\u00fccrelilerde bireyin kendisi ya\u015fant\u0131s\u0131 …<\/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":[6665,6661,2470,2367,6664,6662,6663,5977,6666],"class_list":["post-2690","post","type-post","status-publish","format-standard","hentry","category-fen-ve-teknoloji-odevleri","category-odevler","tag-anafaz-i","tag-homolog-kromozomlar","tag-kromozom","tag-mayoz-bolunme","tag-metafaz-i","tag-oogenesiz","tag-profaz-i","tag-sinaps","tag-telofaz-i"],"_links":{"self":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts\/2690","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=2690"}],"version-history":[{"count":0,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts\/2690\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/media?parent=2690"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/categories?post=2690"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/tags?post=2690"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}