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1、1/53Chapter 8 DNA Replication8.1 Semi-Conservative Replication8.2 Initiation of Replication8.3 Semi-Discontinuous replication8.4 Elongation of Replication and its Proteins8.5 DNA topology8.6 DNA Replication in Eukaryotes8.7 Experiments8.1 半保留复制半保留复制8.2 复制的起始复制的起始8.3 半不连续复制半不连续复制8.4 复制延伸复制延伸 及其相关蛋白及其
2、相关蛋白8.5 DNA拓扑学拓扑学8.6 真核生物真核生物 DNA复制复制8.7 实验研究实验研究2/53DNA ReplicationGenetic information is also passed from generation to generation.A crucial property of life is that even the most complex organisms are able to be copied.When one of your cells divides by mitosis,for example,it makes two new cells t
3、hat are essentially perfect replicas of the parent cell.遗传信息也遗传信息也从一个世代从一个世代到另一个世代到另一个世代进行传递。进行传递。生命至关重要的特性是：生命至关重要的特性是：即使是最复杂的生命也即使是最复杂的生命也能够被复制出来。例如，能够被复制出来。例如，当你的细胞进行有丝分当你的细胞进行有丝分裂时，它能产生两个本裂时，它能产生两个本质上是母细胞完美复制质上是母细胞完美复制品的新细胞。品的新细胞。8.1 Semi-ConservativeReplication /半保留复制半保留复制Semi-conservative repl
4、ication:A style of DNA replication in which produces a DNA with one strand from the parent,and one newly synthesized strand.半保留复制：半保留复制：一种一种DNA的复的复制方式，产生的制方式，产生的DNA中一条中一条链来自于母本、另一条链是链来自于母本、另一条链是新合成的。新合成的。4/538.2 Initiation of Replication/复制的起始复制的起始5/53Bidirectional Replication/双向复制双向复制8.3 Semi-disco
5、ntinuousreplication半不连续复制半不连续复制7/53Semi-discontinuous replication/半不连续复制半不连续复制8/53Semi-discontinuous replication/半不连续复制半不连续复制9/538.4 Elongation of Replicationand its Proteins复制延伸及其相关蛋白复制延伸及其相关蛋白8.4.1 Helicase and SSBs8.4.2 DNA polymerase III8.4.3 Explanation for 35 Synthesis8.4.4 Primers8.4.1 解旋酶与解旋
6、酶与SSB8.4.2 DNA聚合酶聚合酶III8.4.3 关于关于35合成合成8.4.4 引物引物10/538.4.1 Helicase and SSBs /解旋酶与解旋酶与SSB11/533D structure of helicaseFile:E coli helicase 2J0Q.val12/53SSB:single-strand DNA binding proteinssDNAssDNAFile:E coli SSB bound to ssDNA 1EYG.val13/538.4.2 DNA polymerase III /DNA聚合酶聚合酶III14/53DNA polymeras
7、e III corePolymerizationProofreading15/53Sliding clamp /滑行夹滑行夹16/53Safety clamp for climbing /攀岩安全攀岩安全扣扣 17/533D structure of sliding clampFile:E coli DNA pol III beta dimer 1MMI.val18/53Clamp loader /滑行夹加载器滑行夹加载器19/533D structure of clamp loaderFile:E coli clamp loader gamma complex of DNA pol III.
8、val20/53Proofreading /校正校正35 exonuclease activity35外切核酸酶活性外切核酸酶活性21/53Proofreading /校正校正22/53Now showingDNA ReplicationFile:biophoto7 Life DNA Replication,Part 2:Coordination of Leading and Lagging Strand Synthesis 23/53Now showingDNA polymerizationFile:biophoto7 Lehninger Nucleotide polymerization
9、by DNA polymerase.(5)24/538.4.3 Explanation for 35 Synthesis关于关于35合成合成53 Synthesis continues after proofreading35 Synthesis stops after proofreading 25/5353 Synthesis continues after proofreading26/5353 Synthesis continues after proofreading27/5335 Synthesis stops after proofreading 28/5335 Synthesi
10、s stops after proofreading 29/538.4.4 Primers /引物引物30/53Primer for Okazaki fragment31/53Primer Removal /引物去除引物去除32/538.5 DNA topology /DNA拓扑学拓扑学33/53Topoisomerase I /拓扑异构酶拓扑异构酶I34/53Topoisomerase II /拓扑异构酶拓扑异构酶IITermination of replication in E.coli大大肠肠杆杆菌菌复复制制终终止止36/538.6 DNA Replication in Eukaryot
11、es真核生物真核生物DNA复制复制Prokaryotic DNAEukaryotic DNA1000 nt/sec1000 nt/min37/53Multiple initiation sites多重起始位点多重起始位点www.usask.ca/./replication/replication.htm 38/535 eukaryotic DNA polymerasesEukaryotic DNA polymerasesPol (Synthesis of lagging strand)Pol (Synthesis of leading strand)Pol (Function unknown)
12、Pol (DNA repair)Pol (Replication of mitochondrial DNA)Pol IIIPol I3 prokaryotic DNA polymerasesPol II?39/538.6.1 Replication initiation in Eukaryotes真核生物复制起始真核生物复制起始S.cerevisiae（面包酵母）面包酵母）www2.biomed.cas.cz/benada/lem117/eng/stereo.htm ARS:autonomouslyreplicating sequence自主复制序列自主复制序列 OriC40/53Eukary
13、otic replication origins真核生物复制起点真核生物复制起点In higher eukaryotes,it has been much more difficult to pinpoint sequences that serve as origins of replication.In some cases the site of the origin may vary over thousands of bases,in other cases there seem to be no consistent sites of replication origin.Fact
14、ors other than base sequence,such as nucleosome density,may play important roles in determining the origin.在更高等的真核生物中，在更高等的真核生物中，要找出作为复制起点序列要找出作为复制起点序列的确切位置要困难得多。的确切位置要困难得多。在有些情况下，复制起点在有些情况下，复制起点的序列可能会相差几千个的序列可能会相差几千个碱基，在另一些情况下则碱基，在另一些情况下则看起来根本没有统一的复看起来根本没有统一的复制起点位置。这时，在决制起点位置。这时，在决定复制起点中起重要作用定复制起点中
15、起重要作用的是一些其它因素如核小的是一些其它因素如核小体密度等，而不是碱基序体密度等，而不是碱基序列。列。41/53The cell cycle /细胞周期细胞周期42/53pre-RC:pre-Replicative Complex前复制复合体前复制复合体pre-RC43/53pre-RC:pre-Replicative Complex前复制复合体前复制复合体44/53Cdk2 and Cdc45Inactive Cdk2Active Cdk2Cdc45Cdc4545/538.6.2 Telomeres /端粒端粒Another challenge faced by eukaryotes d
16、uring synthesis is what to do with primers at the end of the chromosome.The end of a eukaryotic chromosome is called the telomere.真核生物真核生物DNA合成面合成面临的另一个挑战是如临的另一个挑战是如何处理位于染色体末何处理位于染色体末端的引物。真核生物端的引物。真核生物染色体的末端称为染色体的末端称为端端粒粒。46/53Telomeres /端粒端粒47/53Telomerase /端粒酶端粒酶 (1/2)48/53Telomerase /端粒酶端粒酶 (2/2)
17、49/53Telomerase and cancer cell端粒酶与癌细胞端粒酶与癌细胞In normal cellNo telomeraseIn cancer cellTelomerase50/538.7 Experiments /实验研究实验研究+Semiconservativereplication半保留复制半保留复制+Conservativereplication保留复制保留复制+Dispersivereplication散乱复制散乱复制51/53The Meselson-Stahl Experiment 52/53Experimental evidenceG0G1G253/53Now showingThe Meselson-Stahl Experiment File:biophoto7 Life The Meselson-Stahl experiment(10)