分子生物學(xué)的中心法則-文庫吧
2024-12-18 05:12 本頁面
【正文】 止 Transcription RNA polymerase,RNA聚合酶 closed promoter plex,封閉的啟動(dòng)子復(fù)合物 open promoter plex,開放的啟動(dòng)子復(fù)合物 initiation elongation termination RNA product RNA chains are synthesized in a 5’ to 3’ direction Prokaryotic RNA polymerase structure RNA polymerase of E. coli is a multisubunit protein Subunit Number Role a 2 uncertain b 1 forms phosphodiester bonds b? 1 binds DNA template s 1 recognizes promoter and facilitates initiation a2bb’ s a2bb’ + s holoenzyme core polymerase sigma factor RNA polymerase holoenzyme (+ s factor) ? closed promoter plex (moderately stable) ? the sigma subunit binds to the 10 region ? once initiation takes place, RNA polymerase does not need very high affinity for the promoter ? sigma factor dissociates from the core polymerase after a few elongation reactions ? elongation takes place with the core RNA polymerase ? open promoter plex (highly stable) ? the holoenzyme has very high affinity for promoter regions because of sigma factor s ? sigma can rebind other core enzymes The sigma cycle s s 四、遺傳密碼 ? The Geic Code: Translation of RNA code into protein 三聯(lián)體密碼子的特點(diǎn)： 1）方向性 2）無標(biāo)點(diǎn)性 3）簡(jiǎn)并性 4）通用性 5）擺動(dòng)性 起始密碼子： ATG。 終止（無義）密碼子： UAA UGA UAG。 同義密碼子： 編碼同一個(gè)氨基酸 的幾個(gè)密碼子。 五、翻譯 Translation is the process of converting the mRNA codon sequences into an amino acid sequence. Translation，翻譯：在 RNA控制下，根據(jù)核酸鏈上每三個(gè)核苷酸決定一個(gè)氨基酸的三聯(lián)體密碼規(guī)則，合成出具有特定氨基酸順序的蛋白質(zhì)肽鏈的過程。 Protein Synthesis and Protein Processing a). RNA structure b). Protein synthesis i). Initia
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