Home / Biologiya / POLIMERHOI BIOLOGI – KISLOTAHOI NUKLEINAT

POLIMERHOI BIOLOGI – KISLOTAHOI NUKLEINAT

Ahamiyati kislotahoi nukleinat dar hujayrahoi organizm nihoyat kalon ast. Hususiyati sokhti khimiyavii onho imkoniyati nigahdori, guzaronidan va intiqoli irsiyatro tamin menamoyad. Azbaski sababi aksariyati khosiyatho va alomatho dar organizmi zinda safedaho meboshand, binobar in fahmost, ki ustuvorii kislotahoi nukleinat – sharti muhimtarini mutadili faoliyati hayotii hujayra va tamomi organizm ba shumor meravad. YAne, metavon guft, ki zuhuri khosiyat va funksiyai kislotahoi nukleinat ba khosiyat va funksiyahoi safedaho dar organizm sakht vobasta ast.

Har guna tagyirot dar sokhti kislotahoi nukleinat ba tagyiroti strukturai hujayra yo faoliyati ravandhoi fiziologi dar onho ovarda merasonad.

Strukturai kislotahoi nukleinat bori avval az tarafi biologi amerikoi J.Uotson va fiziki anglis F.Krik omukhta shuda bud. Onho izhor namudand, ki tadqiq va fahmishi alomatho dar organizmi zinda, hamchunin tadqiqi qonuniyathoi ijroi funksiyai chi hujayrahoi alohida va chi sistemai hujayraho-boftaho va uzvho ahamiyati khele kalon dorad.

Dar organizm du navi kislotahoi nukleinat–kislotai dezoksiribonukleinat (KDN) va kislotai ribonukleinat (KRN) mavjudand.

Kislotai dezoksiribonukleinat – KDN. Kislotai dezoksiribonukleinat polimeri biologi buda, az du zanjiri (silsilai) polinukleotidi, ki bo hamdigar payvast shudaand, iborat ast. KDN polimeri massai molekulaviash khele kalon meboshad.

Monomerhoe, ki zanjirhoi KDN-ro tarkib medihand, payvastagihoi murakkabi organiki buda, asoshoi nitrogeni dorand: adenin (A) yo timin (T), sitozin (S) yo guanin (G), qandi panjatoma-pentoza-dezoksiriboza, ki az rui on khudi KDN nom giriftaast, inchunin boqimondai kislotai fosfat. In payvastagiho nukleotidho nomida shudaand (rasmi 3.6).

polimerkhoi biologi

Dar yak molekula 108 va beshtar nukleotidho dokhil meshavand. Dar har zanjir nukleotidho bo hamdigar tavassuti bandi fosfodiefirii bayni yak dezoksiriboza va boqimondai kislotai fosfati nukleotidi badina payvast shudaand. Du zanjir dar molekulai yagona bo yorii bandhoi gidrogeni, ki bayni asoshoi nitrogeni ba vujud meoyand, muttahid meshavand. Asoshoi nitrogeni ba tarkibi nukleotidho, ki silsilahoi gunogun ba vujud meorand, dokhil shudaand. Miqdori bandhoi gidrogeni bayni asoshoi nitrogenii gunogun nobarobar ast, az hamin sabab onho faqat metavonand juftjuft (dutoi) payvast shavand: asosi nitrogenii A-i yak zanjiri polinukleotidho hamesha bo T-i digar zanjir, vale

G–bo se bandi gidrogeni bo asosi nitrogenii S muqobili silsilai polinukleotidi payvast meboshand. Hamin gunna qobiliyati intikhobii payvastshavii nukleotidho, ki dar natijai on jufthoi A–T va G–S ba vujud meoyand, qobiliyati komplementari nomida meshavad (rasmi 3.7).

555

Agar paydarhamii asoshoi nitrogeni dar yak zanjir (ma- salan, T–S–A–T–G) malum boshad, on goh ba tufayli prinsipi komplementari paydarhamii asoshoi nitrogenii zanjiri muqobil (A–G–T–A–S) malum megardad.

Zanjiri nukleotidho spiralhoi hajmii rost pechutobkhuranda ba vujud meorand, ki dar har pech 10 juft asosi nitrogeni dorand. Guruhhoi qandfosfatii nukleotidho az berun, vale nukleotidhoi payvastashon komplementari az

darun joygir meboshand. Zanjirho dar atrofi hamdigar, inchunin dar atrofi mehvari umumi pechutob mekhurand (rasmi 3.8). Strukturai chunin molekula asosan bo bandhoi gidrogeni nigoh doshta meshavand.

spirralSpirali duchandai Uotson va Krik Hangomi payvastshavi bo safedahoi muayyan (gistonho) darajai spiralshavii molekulaho meafzoyad. Molekula gafstar va kutohtar megardad (rasmi 3.9). Minbad spiralshavi ba darajai oli merasad va spirali darajaash balandtar superspiral ba vujud meoyad.

Funksiyai KDN. Kislotai dezoksiribonukleinat funksiyai benihoyat muhim – nigoh doshtanu az nav ba vujud ovardani hayotro ijro menamoyad.

YAkum, nigohdorii akhbori irsi, ki ba paydarhamii nukleotidhoi yake az silsilahoi on asos yoftaast. Vohidi khurdtarini akhbori genetiki bad az nukleotid se nukleotidi payiham joygirshuda – triplet meboshad. Paydarhamii triplethoro dar zanjiri polinukleotidi paydarhamii aminokislotaho dar molekulai safeda muayyan mesozad. Dar payi hamdigar joygirshavii tripletho, ki sababi strukturai yak zanjiri polipeptidi megardad, maqomi gen kalon ast.

Загрузка...

Dar boramon

Инчунин кобед

dandon-pizishk

Homiladoron chitavr dandonhoro nigohubin namoyand

Tashrifi dandonpizishk har nim sol, yak marotiba tavsiya karda meshavad. Bo faro rasidani davrai homiladori …