RESESSIVIYaT

RESESSIVIYaT (az lotini gesezziz — dur shudan), yake az shaklhoi genotipii zohir gardidani genhost. G. Mendel hangomi duragakunii fardhoi bo alomathoi muayyan az hamdigar farqkunanda oshkor namud, ki dar duragahoi nasli avval yake az alomathoi padariyu modari (alomati resessivi) nest shuda, digarash (alomati dominanti) paydo meshavad (nigared niz Qonununi Mendel). Shakli dominanti (alleli)-i gen (A) tasiri khudro dar holati gomo va geterozigoti (AA, Aa) va alleli resessivi (a) boshad, faqat hangomi nabudani alleli dominanti (—a) zohir mekuvad. Dominanti yo Resessiviyati allelho faqat hangomi tasiri mutaqobili jufti konkretii genhoi alleli muayyan megardad. Kharakteri zohirshavii alomati resessivi az tasiri muhiti beruna tagyir yofta metavonad. Masalan, pashshai drozofilla mutasiyai resessivi («bolhoi ibtidoi») dorad, ki on dar holati gomozigoti hangomi optimali budani harorat (25°Selsiya) boisi khurd shudani andozai bolho va barobari to 30°Selsiya baland shudani harorat boisi kalon shudani andozai bolho megardad. Tasiri resessivii gen ba sust shudan yo tagyir yoftani jarayoni in yo on funksiyai biokhimiyavi niz vobasta ast. Masalan, dar odam bisyor holathoi modarzodiiinkhtiloli mubodilai modda az nasl ba nasl dar namudi resessivi meguzarad, yane bemori faqat dar gomozigotho mushohida meshavad; dar geterozigotho bodnad, ba tufayli mavjud budani allelhoi dominanti bemori zohir namegardad. Aksar mutasiyahoi resessivi jarayoni prosesshoi biokhimiyavii hayotan mu-himro vayron karda, boisi halokati fardho meshavand. Binobar in muayyan kardani chunin mutasiyaho dar chorvodori va rastaniparvari ahamiyati kalon dorad. Mutasiyahoi resessivi dar prosessi evolyusiya roli kalon mebozand.