MUTAGENEZ

MUTAGENEZ (az lot. mutatio – tagyiryobi va yun. genesis – paydoish), ravandi tagyiroti irsi – mutatsiya, ki az tasiri sharoiti tabii (khud az khud) yo omilhoi gunoguni fiziki yo khimiyavi (mutagenho) ba vujud meoyad. Asosi M.-ro tagyiryobii molekulahoi kislotahoi nukleat, ki nigahdor va noqili akhbori irsi meboshand, tashkil medihand. In tagyirot chun mutatsiyahoi geni yo tashakkuli navi khromosomaho ifoda meyobad. Mekhanizmi M. baroi mutagenhoi gunogun har khel ast. Afkanishoti ionnok ba kislotahoi nukleat bevosita tasir namuda, atomhoi onhoro faol va ionizatsiya mekunad. In boisi kanda shudani silsilai (zanjiri) angishtobu fosfatii molekula va bandhoi gidrogenii bayni torhoi komplementarii KDN (kislotai dezoksiribonukleat) megardad.
Ba rafti M. omilhoi gunoguni beruni tasiri ziyod merasonand, mas., dar zeri tasiri afkanishoti ionnok surati mutatsiyaho hangomi ba hujayra dokhil shudani oksigen afzuda, hangomi norasoii on (agar afkanish dar atmosferai nitrogen ba vujud oyad) sust meshavad. Baze moddaho M.-ro bozmedorand. Mas., ba hujayra firistodani adenozin yo guanozin tasiri mutagenii analoghoi purinii asoshoi nitrogeniro bozmedorad, fermenti katalaza samarai mutagenii afkanishi ionnokro sust mekunad. Hangomi tasiri baze mutagenhoi khimiyavi mutatsiya yakbora yo badi chand vaqt, bazan badi ivaz shudani chand nasli hujayra ba vujud meoyad.