Dar hujayra mutassil ravandkhon sintezi bio- logy meguzarand. Bo yorii fermentho az moddahoi sodai khurdmolekula payvastahoi murakkabi ka- lonmolekula sintez meshavand: az aminokislo- taho – safeda, az monosakharidho angishtobhoi murakkab, az asoshoi nitrogeni va qandho – nu- kleotidho, az onho kislotahoi nukleini.
Majmui reaksiyahoi sintezi biologi mubo- dilai plastiki yo assimilyatsiya nomida meshavad. Ravandhoi muqobili sintez dissimilyatsiya no- mida shudaast, ki on majmui reaksiyahoi tajziya- shavi (parakhashavi) meboshad. Dar vaqti tajziyai payvastahoi kalonmolekula energiya khorij me- shavad, ki on baroi reaksiyahoi sintezi biologi zarur ast.
Reaksiyahoi sintezi biologi bo khususiyati jinsi va fardy farq mekunand. Strukturai sintezi molekulahoi organikii ka- lon bo paydarhamii nukleotidho dar KDN, yane genotip muay- yan megardad. Ravandhoi mubodila bo muhiti dokhilii organizm – gomeostaz – dar mutassil tagyiryobii sharoiti hasti tamin me- shavad. Ba in ravandho, hamchunin ravandhoi sintez – mubodilai plastiki va reaksiyai tajziya, ki dar natijai onho energiya judo shuda, dar bandhoi makroenergii ATF zakhira megardad, tobe meboshand. Moddahoi sintezshuda dar jarayoni sabzish baroi bunyo- di hujayraho va organoidhoi onho, inchunin, baroi ivaz gardi- dani molekulahoi sarfgashta yo vayronshuda istifoda meshavand. Tamomi reaksiyahoi sintez bo furu burda shudani energiya megu- zarand.
- 1. ANABOLIZM
Majmui reaksiyahoi sintezi biologi mubodilai plastiki yo anabolizm (az yunoni apao1e – avj) nomida meshavad. Nomi in namudi mubodila mohiyati onro inikos menamoyad: az moddahoi soda, ki az berun ba hujayra dokhil meshavand, moddahoi monand ba moddahoi hujayra ba vujud meoyand, yane assimilyatsiya meguzarad. Hamai ravandhoi mubodilai moddaho dar hujayra va kulli orga- nizm zeri nazorati dastgohi irsy meguzarand va in natijai amaly gardidani akhbori genetiki meboshad, ki on dar hujayra voqe ast.
Aknun yake az ravandhoi muhimtarini zuhuroti akhbori irsi hangomi mubodilai plastiki – sintezi biologii safedahoro dida mebaroem.
Amaly gardidani akhbori irsy – sintezi biologii safedaho
CHi tavre qayd kardem, hamai gunogunii khosiyati molekulahoi safedagi dar nihoyati kor bo strukturai yakumini onho, yane bo paydarhamii aminokislotaho muayyan megardad. Baroi sintez shudani safeda, akhbor oid ba paydarhamii (payiham joygirsha- vii) aminokislotaho dar strukturai yakumini on boyad ba riboso- ma rasonda shavad. In ravand du davra yo khud du marhalaro dar bar megirad: transkripsiya va translyatsiya.
Transkripsiya (az lotini 1gap8spr1yu – runavis kardan). Akhbor bo rohi dar yake az silsilahoi molekulai KDN sintez shudani mole- kulai yaksilsilai KRN ba vujud meoyad, ki paydarhamii nukleotidhoi on ba paydarhamii nukleotidhoi matritsa (modari) – zanjiri polinukleotidii KDN muvofiqat mekunad. Mekhanizmi makhsusi «donistani» nuqtai ibtidoii sintezi safeda, intikhobi zanjiri KDN, ki bo on akhbor hisob karda meshavad, hamchunin, mekhanizmi anjomyobii ravand mavjud ast.
Dar prokariotho (bakteriyaho), ki yadroi tashakkulyofta nado- rand, ribosomaho ba molekulai az nav sintezshudai KRN-a zud badi judoshavii on az KDN, yo hatto, to anjom yoftani sintezi purrai on, payvast shuda metavonand.
Translyatsiya (az lotini 1gap81a1yu – dodan). Davrai digari sin- tezi biologi – guzaronidani akhbore, ki dar paydarhamii nukleo- tidho (paydarhamii kodonho)-i molekulai KRN-a joy dorad, dar paydarhamii aminokislotahoi zanjiri polipeptidi meboshad.
Dar eukariotho KRN-a dar ibtido boyad tavassuti pardai yadro ba sitoplazma rasonda shavad. Guzaronish bo safedahoi makhsus ba amal ovarda meshavad, ki bo molekulai KRN kompleks hosil menamoyand. In safedaho KRN-a-ro az tasiri zararnoki fermenthoi sitoplazmagi muhofizat mekunand. Dar sitoplazma dar yake az nughoi KRN-a ribosoma faoliyat namuda, sintezi po- lipeptid ogoz meyobad.
Ribosoma dar molekulai KRN-a nomuntazam (nomurattab), triplet az pasi triplet joygir meshavad (rasmi 4.2). Ba andozai joygirshavii ribosoma dar molekulai KRN-a, dar zanjiri po- lipeptidi payi hamdigar aminokislotaho joy megirand, ki ba tripleti KRN-a muvofiqand. Muvofiqshavii durusti aminokis- lotahoro ba kodi tripleti KRN-a KRN-n tamin menamoyad. Har yak aminokislota KRN-n khudro dorad.
YAke az tripletho – antikodon ba tripleti muayyani KRN-a jiddan komplementar meboshad. Hamchunin, ba har kadom amino- kislota fermenti muayyan muvofiqat menamoyad, ki onro ba KRN-n payvast mekunad. Prinsipi umumii dodani akhbori irsy doir ba strukturai molekulahoi safedagi dar ravandi sintezi biologii zanjiri polipeptidi dar rasmi 4.3 nishon doda shudaast.
Badi anjom yoftani sintez zanjiri polipeptidi az matritsa molekulai KRN-a judo shuda, sipas strukturai seyuminro sohib meshavad, ki ba safedai mazkur khos ast.
Molekulai KRN-a baroi sintezi polipeptidho misli ribo- soma, mumkin takroran istifoda shavad. Dar in jo mafhumhoi transkripsiya va translyatsiya ba tavri khele odi va mukhtasar tav- sif karda shudaand. Dar khotir boyad dosht, ki sintezi biologii safedaho – ravandi khele murakkab buda, ba ishtiroki bisyor fer- mentho va sarfi mikdori ziyodi energiya vobasta ast.
Sintezi biologii molekulahoi gayrisafedagi dar hujay- raho dar se davra ba amal meoyad. Dar ibtido doir ba strukturai safeda – fermenti makhsus akhbor ba vujud meoyad, bad bo yorii in ferment molekulai muayyani angishtob yo lipid hosil meshavad. Bo hamin roh dar organizm digar molekulahoi gayrisafedagi – vitaminho, gormonho va gayra niz hosil meshavand.
Savolho baroi sanjish:
- Sintezi biologi az chi iborat ast? Misolho ored. Sintezi biolo- gi az sintezi khimiyavi az kadom jihat fark, mekunad?
- Ravandi assimilyatsiyaro tarif dihed.
- Kodi genetiki chist?
- Hosiyathoi asosii kodi genetikiro gued.
- Kislotahoi ribonukleinat dar kujo sintez meshavand?
- Sintezi safeda dar kujo ba amal meoyad? SHumo ba khosiyat va nak,- shi safedaho, inchunin kislotahoi nukleinat dar organizm chi tavr baho doda metavoned?
Testho
- Majmui ravandi reaksiyahoi sintezi biologiro chi menomand?
a) anabolizm; b) katabolizm; v) denaturatsiya.
- Assimilyatsiya chi mano dorad?
a) az hisobi moddai soda dar huchayra sintez shudani moddahoi orga- niki; b) tachziya shudani moddaho dar organizm; v) sintezi ATF.
- Sintezi safedaho dar kadom qismi huchayra amali megardad?
a) ribosomaho; b) mitokhondriyaho; v) plastidho.
- Az molekulai KDN nuskhabardor shudani KRN – a-ro chi menomand? a) transkripsiya; b) translatsiya; v) terminatsiya.
- Ravandi guzashtani akhbori irsi az KRN- a bo zanchiri polipepti- dii safedaro chi menomand?
a) translokatsiya; b) translatsiya; v) transkripsiya.
- Aminokislotahoro baroi sintez shudani safeda dar ribosoma ka- dom KRN tamin menamoyad?
a) KRN – r; b) KRN – a; v) KRN – n.