dna的復制ppt課件-wenkub
2023-05-16 18:05:00 本頁面
【正文】 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, and they recruit 2 prepriming plexes of DnaBDnaC to bind, so that there is one for each of the two (bidirectional) replication forks. ? DnaB protein is delivered to oriC by DnaC protein in the form of a hexameric (DnaB:DnaC)6 plex, but DnaC protein does not enter the protein assemblage at oriC . ? DnaB protein has helicase activity and it further unwinds the DNA in the prepriming plex in both directions, assisted by DNA gyrase. SSB tetramers coat singlestranded regions as they arise . ③ Primer synthesis: each DnaB activates a DnaG primase, in one case to initiate the leading strand, and in the other to initiate the first Okazaki fragment of the lagging strand. （二）復制的延伸： 1. 復制體：酶和相關蛋白在復制叉形成的超分子復合物 2. 先導鏈和后隨鏈的同時復制 ? Lagging template strand通過復制體形成一個環(huán)狀結構， primase已經(jīng)合成一條引物＃ 2 ? 隨著岡崎片段的合成，環(huán)逐漸變大，直到＃ 2片段末端接近前一岡崎片段的引物 ? 復制體釋放環(huán)， primase合成一個新的引物 3. 環(huán)型 DNA的復制類型： ① θ型（ ） : an origin creates two replication forks that move in opposite directions ② Dloop (mammalian mitochondrial DNA)： ? mtDNA的復制在 H鏈的復制起點 OH開始合成 。創(chuàng)世紀 》 第一節(jié) DNA復制概貌 一、 DNA復制的半保留性 二、復制過程中的順序性 ?復制從原點開始 ?邊解鏈邊復制 ?
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