GENETIKA

GENETIKA (yun. genesis – paydoish), ilmest dar borai irsiyat va tagyirpazirii organizmho.
Tasavvuroti avvalin dar borai tabiati irsiyat va tagyirpaziri hanuz dar ibtidoi tarikhi bashariyat bayon yofta bud. On dar asosi mushohidai odam doir ba hayvonoti khonagi, rastaniho va khudi u ba vujud omad. Odam hanuz dar hamon davraho baroi boztavlid az hamon hayvonot va rastanihoe istifoda mekard, ki sifathoi khubi onho beshtar zuhur yofta budand (yane u dar doirai jinsho intikhobi muayyan meguzarond). CHunin seleksiyai sodda ba odam imkon dod, ki hayvonoti gunoguni khonagi va rastanihoi bogiro ba vujud ovarad. YAkumin asari ilmi dar borai irsiyat va tagyirpaziri dar a. 17 paydo shudaast. On talifi Kamerarius «Qaydho dar borai jinsi rastaniho» bud. u dar in asarash ba khulosa meoyad, ki rastaniho ham misli hayvonot jins dorand va gardolud shudani yak navi rastani bo gardi navi digar boisi paydoishi shakli komilan nav megardad. Dar ibt. a. 18 tavsifi nakhustini chunin duragaho paydo shud.
Qonunhoi asosii G.-ro s. 1866 tabiatshinosi chekh Gregor Mendel dar natijai tajriba bo navhoi gunoguni nakhud muqarrar kard. Mendel ba khulosa omad, ki meros giriftani har yak alomatro yagon omil (yo omilho)-e, ki az hujayrahoi jinsi meguzarad, muayyan mekunad; alomathoi organizmho hangomi duraga kardan nest nameshavand, balki onhoro naslho muvofiqi qonuniyathoi muayyan ba meros megirand. Dertar onho « Qonunhoi Mendel» nomida shudand. Garchande ki Mendel dar borai mavqei omilhoi irsi dar hujayra, tabiati khimiyavii onho va tarzi tasir ba in yo on alomat chize namedonist, bo vujudi in talimoti u dar borai omilhoi mazkur chun vohidi irsiyat asosi nazariyai genro tashkil medihad va tarzi tahlili genetikii meros giriftani alomat, ki samarai ejodii ust, usuli asosii genetika ba shumor meravad.
Dar ibtidoi sadai 20 qonunhoi Mendelro, ki hamasronash sarfahm narafta budand, baze biologho «az nav kashf namudand». Binobar in s. 1900 rasman soli tashakkuli ilmi G. mahsub meshavad.
S. 1906 bo taklifi Beytson ilme, ki irsiyat va tagyirpaziriro meomuzad, G. nomida shud. Zamoni kashfiyoti ajib faro rasid. Hanuz s. 1901 H. de Friz nomurattab tagyir yoftani alomathoi irsiro muqarrar namud va nazariyai ba istiloh mutatsiyaro ejod kard. Dertar T. Morgan va dig. isbot namudand, ki noqili asosii genho khromosomaho buda, onho dar khromosoma ba tartibi khatti joy giriftand.
S. 1944 guruhi tadqiqotchiyon isbot kardand, ki intiqoli alomathoi irsi ba kislotai dezoksiribonukleat – KDN (nig. Kislotahoi nukleat) vobastagi dorad. S. 1953 sokhti molekulai KDN-ro oshkor kardani J. Ustson va F. Krik ba darki mekhanizmi khudtajdidi on va dar ayni zamon baroi ba naslho guzashtani genhoi volidayn imkon dod. Sipas sirri ramzi genetikiro yoftand. Ba tavassuti on dar qismhoi molekulai KDN (genho) malumoti roje ba sokhti safedaero, ki zeri nazorati geni mazkur hosil shudaast, «bo ramz menavishtand». Kashfiyoti minbada G.-ro ba zinai nav bardosht.
Ba vujud ovardani konsepsiya dar borai tarzi tatbiqi akhbori genetiki, ki dar genho ifoda yoftaast, ba davrai navi inkishofi G. zamina guzosht. Kashfi irsiyati khoriji khromosoma, ki sababash tasiri plazmidho meboshad, ahamiyati kalon dorad. In az on sabab ham muhim bud, ki genhoi oshkorsozandai zarari bakteriyaho baroi odam va hayvonot nafaqat dar tarkibi khromosomaho, balki dar tarkibi chunin plazmidho niz oshkor shudand.
Tahkursii G.-i hozirai odam, ki bo omuzishi organizmi inson aloqamand ast, okh. a. 19 guzoshta shud. S. 1875 Galton baroi muayyan kardani mavqei irsiyat va muhit dar inkishofi alomathoi judogonai odam, usuli omuzishi tashakkuli onhoro dar tavamon (dugonikho) peshnihod namud. In tarzi tahqiqi qonuniyathoi genetiki usuli tavamon nom girift. S. 1908 bori nakhust bemorihoi irsii mubodilai moddaho tavsif gardidand; G.-i populyatsiyavii odam, ki sokht va tahrikai tarkibi genhoro dar guruhi mahdudi odamon (populyatsiyaho) meomuzad, ifodai mukhtasari khudro yoft. YAke az muhimtarin vazifai G.-i populyatsiyavii odam «baruikhatgirii» fondi genhoi bashariyat ast. In sohai G.-ro genogeografiya menomand. Peshrafti sohai G.-i populyatsiyavi baroi guzashtan ba tahlili tahavvuli silsilai tomi genho imkon dod, ki on bo peshguii tagyiroti oyanda dar tabiati irsii inson aloqamand ast.
Dar s-hoi 20-umi a. 20 evgenika – talimot dar borai peshgirii ikhtiloli imkonpaziri sifathoi irsii odam paydo shud. Tahqiqi G.-i odam nishon dod, ki irsiyat va tagyirpazirii organizm, hamchunin gunogunii onho ba nishonahoi istedodi irsi va sharoiti zindagi (ijtimoiyu iqtisodi, tabiiyu iqlimi, farhangi va g.) aloqamand ast.
Bahri muhofizati irsiyati odam hifzi on az tasirote, ki boisi mutatsiyai zararnok va margovar megardad, mavqei muhim dorad. SHumorai chunin omilhoi mutageni barobari peshrafti tekhnika dar hayoti odamon meafzoyad.
Dar s-hoi 50-umi a. 20 mavji navi tadqiqot oid ba G.-i odam az sababi peshrafti G.-i umumi va radiatsioni mushohida shud: s. 1956 shumorai aniqi khromosomaho (46) muqarrar gasht; s. 1959 bemorihoi khromosomii odam (sindromi Daun)-ro kshaf namudand.
G.-i odam hamai genhoi har yak khromosoma va alomathoero, ki onho nazorat mekunand, hamchunin sahmi irsiyat va muhitro dar inkishofi alomathoi muqarrari va paydoishi mutatsiya meomuzad. G.-i odam dar hamai in sohaho komyobihoi nazarras ba dast ovardaast. Gunogunshaklii irsi yo polimorfizm az jumlai onhost. CHunonchi, taqr. 200 varianti gemoglobin, shaklhoi ziyodi fermentho va g.-ro kashf kardaand. Bo yorii G.-i biokhimiyavi usulhoi tashkhisi bemorihoi irsiro daryoft mekunand.
Mavjudiyati shumorai ziyodi alomathoi immunologie, ki az jihati genetiki muayyan kardan mumkin ast, isbot shud. Ba chunin alomatho, mas., safedahoi makhsus va karbogidrathoi sathi eritrositho yo leykositho, safedahoe, ki dar molekula qismi karbogidrat (glikoproteid) va muayyankunandai khususiyathoi guruhi khunro dorand, mansub meboshand. In boisi ba sohai mustaqil judo shudani immunogenetika gardid.
Hromosomahoro sitogenetika meomuzad. Olimon muqarrar namudand, ki hujayrahoi omos nisbat ba hujayrahoi muqarrari, odatan, majmui khromosomahoi tagyiryofta dorand. Onho dar jarayoni inkishofi omosi saratoni bo hujayrahoi tagyirnayofta, hamchunin bo yakdigar dar raqobat meboshand.
G.-i odam dar tadqiqoti khud az rui qoidai tasiri mutaqobilai omilhoi biologi va ijtimoi amal mekunad. Malumoti G. guvohi medihand, ki dar masalai peshrafti ijtimoi odam az jihati irsiyat yagon mahdudiyat nadorad. Dar dunyo du shakhsi khususiyathoi irsiashon yakkhela mavjud nest. Az nazari G. hej yak najod yo millat nisbat ba najod yo millati digar bolo nameistad.
Soli 1939 Kongressi II baynalkhalqii genetikon qaror qabul kard, ki ba hamai odamon, sarfi nazar az najod, millat va rangi pust, baroi inkishof imkoniyathoi barobar va purra doda shavand.
Ba tufayli komyobihoi G. sanoati mikrobiologi tashkil yoft. Istehsoli antibiotikho, aminokislotaho, safeda va dig. moddaho dar miqyosi sanoati, ba dast ovardani bakteriyaho, virusho va zanburughoi mikroskopii az jihati genetiki tagyiryofta imkonpazir gardid.
G. baroi halli bisyor masalahoi tibbi, pesh az hama dar muboriza bo bemorihoi siroyati va irsi (nig. Genetikai tibbi) ahamiyati kalon dorad.