生物化学-信息代谢.pptVIP

后随链(the lagging strand)的Okazaki片断只有在一个新的片断合成后，才能被连接成大的片断。 只有在复制叉附近有相当长的单链区时，一个后随链才能启动复制。 由于有后随链的出现，使得DNA的复制并不是连续的，而是半不连续的复制。 前导链 → 连续 后随链 → 不连续 以DNA为模板的DNA聚合酶 * 生物化学 信息代谢 生物代谢 信息代谢 能量代谢 物质代谢 生物代谢 Therefore it must Replicate faithfully. Have the coding capacity to generate proteins and other products for all cellular functions. “A genetic material must carry out two jobs: duplicate itself and control the development of the rest of the cell in a specific way.” -Francis Crick DNA is the Genetic Material DNA Replication April 25, 1953 Watson and Crick: It has not escaped our notice that the specific (base) pairing we have postulated immediately suggests a possible copying mechanism for the genetic material. The Dawn of Molecular Biology The hypothesis of semiconservative replication proposed by Watson and Crick in 1953. Old strand New strand 第一节 DNA的复制 Replication of DNA DNA半保留复制 DNA在提取过程中已经被断裂成许多片段, 因此,只涉及DNA复制前和复制后的状态 冈崎片断不是一个复制子，冈崎片断的合成起始点不是DNA的复制起始点。 DNA半不连续复制 DNA replication is semi-discontinuous Continuous synthesis Discontinuous synthesis 1.5 The Enzymology of DNA Replication DNA Is Synthesized by DNA Polymerases DNA聚合酶I by Arthur Kornberg in 1955 原核生物中。 Discovery of how DNA is assembled helped ignite the biotechnology revolution 模板链结合部位 引物链结合部位 dNTP专一性结合部位 多种酶活性催化部位 识别并结合模板 识别并结合引物 识别并结合4种dNTP 三种酶活性 酶活性部位的复杂性 DNA聚合酶 DNA复制过程及相应酶类 Topoisomerase 以DNA为模板的RNA合成 nNTP (NMP)n + nPPi RNA聚合酶 模板、Mg2+ RNA的转录合成Synthesis of RNA by transcription RNA polymerase performs multiple functions: Searches for initiation sites on the DNA molecule and unwinds a short stretch of DNA (起始); Selects the correct NTP and catalyzes the formation of phosphodiester bonds (延伸); Detects termination signals for RNA synthesis (终止). RNA聚合酶 RNA生物合成过程及其酶类 * *