《分子生物学》课程教学课件（PPT讲稿）Chapter 3 DNA replication

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Chapter 3 DNA replication

Contents Part1 ntroduction of DNA replication概述 Part 2 DNA replication in prokaryotes原核生 物的DNA复制 Part 3 DNA replication in eukaryotes真核生 物的DNA复制 Part4 Fidelity of replication复制的忠实性 Part 5 Application of DNA replication theory DNA复制原理的应用 2025/5/15 2

2025/5/15 2 Part 1 Introduction of DNA replication 概述 Part 2 DNA replication in prokaryotes 原核生 物的DNA复制 Part 3 DNA replication in eukaryotes 真核生 物的DNA复制 Part 4 Fidelity of replication 复制的忠实性 Contents Part 5 Application of DNA replication theory DNA复制原理的应用

Key points: 。 Concepts of semiconservative replication, replication eye,replication fork,replicon, replisome,leading strand,lagging strand. DNA的半保留复制，复制眼、复制叉、复制子、 复制体、前导链、后随链的概念； Features and function of DNA polymerase l, l,l.DNA聚合酶、l、I的性质及功能； Initiation and elongation of replication复制的 起始、延伸； 2025/5/15 3

2025/5/15 3 Key points： • Concepts of semiconservative replication, replication eye, replication fork, replicon, replisome, leading strand, lagging strand. DNA的半保留复制，复制眼、复制叉、复制子、 复制体、前导链、后随链的概念； • Features and function of DNA polymerase I, II, III. DNA聚合酶I、II、III的性质及功能； • Initiation and elongation of replication复制的 起始、延伸；

·Replication of linear DNA ends线性DNA末端的 复制 ·Fidelity control of Replication复制忠实性的控 制 Principles of polymerase chain reaction and sequencing PCR技术及DNA测序技术的原理 2025/5/15 4

2025/5/15 4 • Replication of linear DNA ends 线性DNA末端的 复制 • Fidelity control of Replication复制忠实性的控 制 • Principles of polymerase chain reaction and sequencing PCR技术及DNA测序技术的原理

Part 1 Introduction of DNA replication DNA复制的概况 一、核酸生物合成的一般规则 1.In most cases,the synthesis of DNA or RNA follow Watson- Crick base-pairing rules of A with T and G with C,and copy the pre-existed DNA strand(template).绝大多数 DNA或RNA生物合成，均按照Vatson-Crick碱基互补原则， 以拷贝预先存在的DNA链（模板链）的方式进行。 2.The direction of nucleic acid synthesis:核酸链合成的 方向只有一个：5’→3’。 3.The process of synthesis of DNA or RNA was catalyzed by specific polymerase特异的聚合酶催化合成DNA或RNA。 2025/5/15 5

2025/5/15 5 一、核酸生物合成的一般规则 1. In most cases, the synthesis of DNA or RNA follow Watson￾Crick base-pairing rules of A with T and G with C, and copy the pre-existed DNA strand (template). 绝大多数 DNA或RNA生物合成，均按照Watson-Crick碱基互补原则， 以拷贝预先存在的DNA链（模板链）的方式进行。 Part 1 Introduction of DNA replication DNA复制的概况 2. The direction of nucleic acid synthesis: 核酸链合成的 方向只有一个：5’→3’。 3.The process of synthesis of DNA or RNA was catalyzed by specific polymerase 特异的聚合酶催化合成DNA或RNA

二、 General features of DNA replication DNA复制的基本特征（多数生物） (一) Semiconservative replication DNA的半保留复制 1.definition DNA replication:in which the two strands of a parental duplex separate completely and pair with new progeny strands. One parental strand is therefore conserved in each progeny duplex.DNA复制必须以一条母链为模板以碱基互补的原则合 成新的DNA链，即新合成的DNA双螺旋由一条母链和一条新 合成的 2025/5/15 6

2025/5/15 6 1.definition （一）Semiconservative replication DNA的半保留复制 DNA replication: in which the two strands of a parental duplex separate completely and pair with new progeny strands. One parental strand is therefore conserved in each progeny duplex. DNA复制必须以一条母链为模板以碱基互补的原则合 成新的DNA链，即新合成的DNA双螺旋由一条母链和一条新 合成的子链构成。 二、General features of DNA replication DNA复制的基本特征（多数生物）

2.Hypothesis and evidence of DNA semiconservative replication DNA半保留复制假说的提出及证实： 1)DNA double helix Phosphorus Minor Carbon in groove sugar-phosphate backbone' Hydrogen 3.4nm Oxygen Major groove 0.34nm Bases 二a性☒ 2025/5/15 7

2025/5/15 7 2. Hypothesis and evidence of DNA semiconservative replication DNA半保留复制假说的提出及证实： 1) DNA double helix

2)Three hypotheses for DNA replication 三种DNA复制假说： (a)Semiconservative (b)Conservative (c)Random dispersive 8 Figure 20.1 Three hypotheses for DNA replication

2025/5/15 8 2) Three hypotheses for DNA replication 三种DNA复制假说：

3)Evidence from experiments实验证据： Meselson and Stahl (a) (b) Figure 1.11 (a)Matthew Meselson;(b)Franklin Stahl.(Source:(a) Courtesy Dr.Matthew Meselson.(b)Cold Spring Harbor Laboratory Archives.) They experimentally proved Watson and Crick's model of semi-conservative replication-1958 2025/5/15 9

2025/5/15 9 3) Evidence from experiments 实验证据： Meselson and Stahl They experimentally proved Watson and Crick’s model of semi-conservative replication-1958

15 细菌在含有15N的培养基上生 长多代，使DNA双链充分标记 转入4N培养基中 (a) (b) (c) (a)立即取出 (b)繁殖一代后取出 (b)繁殖二代后取出 提取DNA.CsCI 密度梯度离心 轻带 杂交带 重带 半保留复制证明的实验 Unlabeled Meselson-StahlDNA control 14N4N 双车轻DNA双重DNA 杂交DNA 杂交DNA 双车轻DNA

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