DNA生物合成（英文版）.pptVIP

Sliding clamps dramatically increase DNA polymerase activity. * .biochemistry and molecular biology * * .biochemistry and molecular biology * * .biochemistry and molecular biology * * .biochemistry and molecular biology * NOTE: Concepts of semiconservative replication, replication eye, replication fork, replicon, replisome, leading strand, lagging strand. * .biochemistry and molecular biology * Origin, direction and speed of replication Specific genomic DNA sequences direct the initiation of DNA replication. Origins of replication : A DNA site at which DNA replication begins and which is essential for proper replication to occur. * .biochemistry and molecular biology * oriC of E.coli ： 两种类型的重复序列 Three 13-mers repeat Four nine-mers repeat Rich in A-T 1.3DNA is replicated as a single unit in E.coli Autonomous replication sequence (ARS) of yeast（酵母的自主性复制序列） SV40 virus Features of origins of replication * .biochemistry and molecular biology * Have several unique, short repeated sequences 2. These sequences could be recognized by binding proteins of replication origin 3. Usually there will be an A-T rich sequence near the origins of replication. 对一个生物体基因组而言，复制起点是固定的。 All the DNA replicated from one origin of replication, one origin per replicon. 一般把生物体的复制单位称为复制子，即从一个DNA复制起点起始的DNA复制区域。它是一个独立复制单位，包括复制起点和终点。每个复制子有一个复制起点。 Replicon Prokaryote has single replicon, while eukaryote have multiple replicons. * .biochemistry and molecular biology * Replication speed: 根据染色体DNA的长度、复制所需要的时间和复制子的数目，可以计算出DNA复制的速度： * .biochemistry and molecular biology * Bidirectional replication 复制起始于一个位点，形成两个复制叉，向相反方向运动。在每个复制叉，两条DNA链均被拷贝。 * .biochemistry and molecular biology * 在生物界，复制叉移动的方向和速度虽是多种多样的，但以双向等速方式为主。 DNA Polymerase A DNA polymerase is an enzyme that catalyzes the polymerization of deoxyribonucleotides into a DNA strand. Based on sequence homology, DNA polymerases can be further subdivided into seven different families: A, B, C, D, X, Y, and RT. *