dna的復(fù)制ppt課件-文庫(kù)吧在線文庫(kù)
【正文】 苷酸處，需經(jīng) RNaseH加工后產(chǎn)生有 555個(gè)核苷酸的引物，然后由DNA聚合酶 I在引物的 3‘末端起始 DNA合成。 ? 復(fù)制前，雙鏈上回文序列中的 A都被甲基化。H2B 二聚體 ② 新合成的組蛋白也被組裝成 H32 ? 然后 DNA聚合酶 Ⅰ 從 3’端延伸填補(bǔ)起這個(gè)空缺，留下最后的裂隙由連接酶封閉，產(chǎn)生了一個(gè)連環(huán)分子。 DNA的復(fù)制 God said to them: ―Be fruitful and multiply！” —《 圣經(jīng) ? 再由特異性限制內(nèi)切酶在連接處交錯(cuò)切割，產(chǎn)生 3’ 凹端 ? 由 DNA多聚酶 Ⅰ 在 3’OH上延伸填滿新的空缺，產(chǎn)生兩條完整的雙鏈。H42 四聚體和 H2A子代鏈復(fù)制過(guò)程中，產(chǎn)生半甲基化 DNA。而在基因組其它區(qū)域的 GATC位點(diǎn)，在復(fù)制后 min內(nèi)即被甲基化。主要由一串十分簡(jiǎn)單和串聯(lián)重復(fù)的序列組成 如四膜蟲(chóng)： GGGGTT ? 端粒功能：操持染色體的穩(wěn)定性 ? 端粒酶 (Telomerase) ：一種含RNA的蛋白復(fù)合物，能使端粒延伸。→ 539。Trich DNA is melted. ② Helicase is bound to the plex and creates the replication fork. ③ The first nucleotides of the new chain are synthesized into the primer ① DnaA protein is the initiation factor : ? The four 9 bp consensus sequences on the right side of oriC provide the initial binding sites for DnaA. It binds cooperatively to form a central core around which oriC DNA is wrapped. ? Then DnaA acts at three ATrich 13 bp tandem repeats located in the left side of oriC. In the presence of ATP, DnaA melts the DNA strands at each of these sites to form an open plex ? HU protein has the capacity to bend DNA, and is involved in building the structure that leads to formation of the open plex. ? Transcriptional activation: RNA polymerase could be required to read into the origin from adjacent transcription units. The act of transcription could be associated with a structural change that assists melting of DNA. Hu ② The replication fork is generated ? 24 monomers of DnaA bind at the origin, a
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