replikatsiyaning molekulyar asoslari

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Updated Dec 2025

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ppt/slides/_rels/slide6.xml.rels ppt/slides/_rels/slide5.xml.rels ppt/slides/_rels/slide4.xml.rels ppt/slides/_rels/slide3.xml.rels ppt/slides/_rels/slide1.xml.rels ppt/slides/_rels/slide7.xml.rels ppt/slides/_rels/slide9.xml.rels ppt/_rels/presentation.xml.rels ppt/slides/_rels/slide15.xml.rels ppt/slides/_rels/slide14.xml.rels ppt/slides/_rels/slide13.xml.rels ppt/slides/_rels/slide12.xml.rels ppt/slides/_rels/slide11.xml.rels ppt/slides/_rels/slide10.xml.rels ppt/presentation.xml ppt/slides/slide9.xml ppt/slides/slide6.xml ppt/slides/slide5.xml ppt/slides/slide8.xml ppt/slides/slide3.xml ppt/slides/slide2.xml ppt/slides/slide7.xml ppt/slides/slide15.xml ppt/slides/slide14.xml ppt/slides/slide10.xml ppt/slides/slide11.xml ppt/slides/slide12.xml ppt/slides/slide13.xml ppt/slides/slide1.xml ppt/slides/slide4.xml ppt/slidelayouts/_rels/slidelayout1.xml.rels ppt/slidelayouts/slidelayout4.xml ppt/slidemasters/_rels/slidemaster1.xml.rels ppt/slidelayouts/slidelayout5.xml ppt/slidemasters/slidemaster1.xml ppt/slidelayouts/slidelayout3.xml ppt/slidelayouts/slidelayout2.xml ppt/slidelayouts/slidelayout1.xml ppt/slidelayouts/_rels/slidelayout11.xml.rels ppt/slidelayouts/_rels/slidelayout3.xml.rels ppt/slidelayouts/_rels/slidelayout4.xml.rels ppt/slidelayouts/_rels/slidelayout6.xml.rels ppt/slidelayouts/_rels/slidelayout7.xml.rels ppt/slidelayouts/_rels/slidelayout5.xml.rels ppt/slidelayouts/slidelayout11.xml ppt/slidelayouts/slidelayout10.xml ppt/slidelayouts/slidelayout9.xml ppt/slidelayouts/slidelayout8.xml ppt/slidelayouts/_rels/slidelayout10.xml.rels ppt/slidelayouts/slidelayout7.xml ppt/slidelayouts/_rels/slidelayout9.xml.rels ppt/slidelayouts/slidelayout6.xml ppt/slidelayouts/_rels/slidelayout8.xml.rels ppt/slidelayouts/_rels/slidelayout2.xml.rels ppt/theme/theme1.xml ppt/media/image1.jpg ppt/commentauthors.xml ppt/media/image6.png ppt/viewprops.xml ppt/presprops.xml ppt/tablestyles.xml docprops/core.xml ppt/media/media1.mp4 ppt/media/media2.mp4 ppt/media/media3.mp4 d

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ocprops/app.xml ppt/media/image2.png ppt/media/image3.png ppt/media/image4.png ppt/media/image5.png ppt/media/image7.png ppt/media/image8.png ppt/media/image9.png ppt/slides/_rels/slide2.xml.rels ppt/slides/_rels/slide8.xml.rels [content_types].xml _rels/.rels docprops/custom.xml bugungi kunda replikatsiya jarayonining to`la va aniq tasviri yo`q, bu jarayonda ma’lum funktsiyani bajaradigan yigirmadan ortiq fermentlar va oqsillar ishtirok etsa kerak. dnk replikatsiyasining boshlanish bosqichida ajratuvchi oqsillar ta’sirida dnk molekulasi ichki qismlarida bir yo`la bir nechta replikativ ayrilar hosil bo`ladi. dnk replikatsiyasi initsiatsiyasida ishtirok qiladigan fermentlardan biri – praymaza nomini olgan maxsus rnk-polimeraza bo`lib, u praymer deb ataladigan kalta (4 dan 10 tagacha nukleotiddan iborat) rnk sintezlanishini ta’minlaydi. rnk-polimeraza (praymaza) dnk-polimerazadan farqi tomizg`iga muhtoj emas. hosil bo`lgan rnk zanjiri (praymer) nihoyasidagi ribonukleotidning 3¹ oxiri dnk sintezida uchun tomizg`i vazifasini bajaradi. dnk matritsasida rnk qisqa zanjirini sintezi tugaganidan keyin ferment dnk dan ajraladi. shu guruhga dnk-polimeraza iii yordamida bittadan dezoksiribonukleotidlar ulansa dnk sintezi 5¹→ 3¹ yo`nalishda davom etadi ( zanjir elongatsiyasi) va rnk-dnk gibridli zanjiri hosil bo`ladi. dnkpolimeraza iii dnk ning qisqa fragmentlari (okazaki fragmentlari)ni – replikativ …

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arini hosil bo`lishida, nukleazali faollik esa fosfodiefir bog`larining gidrolizida qatnashadi. dnk polimeraza i replikatsiyadagi rnk-tomizg`ini parchalab uning o`rnida dnk ning komplementar qismini sintezlaydi. dnk-polimeraza ii juda past polimerazali faollikka ega, uning replikatsiyadagi vazifasi aniqlanmagan. dnkpolimeraza iii replikatsiyaning asosiy fermenti bo`lib, dnk qo`sh zanjirining ajralgan zanjirida yangi dnk ning komplementar qismini 5¹→ 3¹ yo`nalishda sintezlaydi . 2. ― tomizg`i dnk ga bog`liq (to’be bo`lgan) rnk polimeraza – odatda transkriptsiyada ishtirok etadigan fermentlar – rnk-polimerazalarning alohida varianti bo`lib, replikativ vilkadagi dnk ning komplementar qismida rnk ―tomizg`i (― praymer) hosil qiladi. rnk-tomizg`ining sintezi 5¹ oxiridan 3¹ oxiriga qarab boradi. nukleotidlarni rnk da joylashish tartibini dnk – matritsa belgilab beradi, nukleotidlarning 5¹→ 3¹ fosfodiefir bog`lari yordamida bog`lanishi rnk-polimeraza ishtirokida amalga oshadi. dnk ning replikatsiya mexanizmi dnk replikatsiyasi uchun quyidagilar talab qilinadi: 1 ) dnk yangi zanjiri uchun struktura materiali sifatida dezoksiribonukleozidtrifosfatlar (datf, dgtf, dstf, dttf) bo`lishi kerak; 2 ) dnk qo`sh zanjirini yechilishi; 3 …

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a dnk-polimeraza i bilan birga ishtirok etadi . 5. dnk-ligazalar (biriktiruvchi fermentlar). yangi sintezlangan dnk qismlarini bir-biri bilan bog`lash vazifasini bajaradigan bir nechta fermentlar aniqlangan . dnk-ligazalar nad + dan adenilil manbai sifatida foydalanib, 3¹→ 5¹ fosfodiefir bo`g`larini hosil qiladi. e’tiboringiz uchun raxmat ! dnk reparatsiyasi. dnk bitta zanjirining buzilgan qismini to`g`rilanishi yoki reparatsiyasini chegaralangan replikatsiya sifatida qarash mumkin. masalan , teri epitelial hujayrasi dnk zanjirini ultrabinafsha nurlar ta’sirida zararlaganda kuzatiladigan reparatsiya jarayoni ancha mukammal o`rganilgan. rnk-tomizg`i dnk-polimeraza iii ta’sirida maxsus ribonukleaza h yoki dnk polimeraza i yordamida to`liq ajralib chiqadi. rnk-tomizg`i egallagan joyda dnk-polimeraza i yordamida dnk zanjiri o`sa boshlaydi. sintezlangan dnk fragmentlari (okazaki fragmentlari)ni birikishi 3¹→ 5¹ yo`nalishida dnkligaza yordamida amalga oshadi. keyingi tekshirishlar dnk sintezining initsiatsiyasi yana ham murakkab ekanligini ko`rsatdi. praymaza ta’siri oldidan kamida 5 ta oqsildan iborat kompleks hosil bo`lishi zarur ekanligi aniqlandi. oqsillardan biri atf energiyasidan foydalanib , dnk zanjiri bo`ylab harakatlanadi, bu esa …

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a bo`laklarni yechib beradilar ; buning uchun 2 molekula atf gidrolizidan hosil bo`ladigan energiya kerak . ajralgan zanjirlar qaytadan qo`shilib ketmasligi uchun dnk-bog`lovchi oqsillar , replikatsiya jarayonida zanjirlarning juda tez yechilishida uzilib ketmasligi uchun giraza (guration – aylanish so`zidan olingan), eukariotlarda topoizomeraza va yana bir qator fermentlar va oqsillar, matritsa va initsiatorlar qatnashadi. dnk-giraza fermenti yordamida qisqa ajralish va birikishlar sodir bo`ladi. u xelikazaga replikatsiya uchun dnk ni qayta aylantirishga yordam beradi. zanjirlarning yoyilishida har bir qo`sh asosning ajratilishi uchun ikki molekula atf – gidroliz energiyasi sarf bo`ladi. umuman, dnk ning yoyilishi dnk replikatsiyasining eng qiziqarli va eng murakkab muammolaridan biridir. 1969 yilda yapon olimi reydji okazaki har ikkala zanjir bir vaqtda replikatsiya qilinganda bir zanjir uzluksiz, ikkinchi yangi zanjir esa kalta fragmentlar shaklida sintezlanishini kashf etdi. uzluksiz sintezlanadigan zanjir―boshlovchi, uzilib sintezlanadigani ― kechikkan zanjir deb ataladi. so`ngra okazaki fragmentlarining sintezi uchun tomizg`i sifatida rnk ning kichik bo`lakchalari kerak ekanligi …

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