[理学]20杨DNA_replication.pdf

Chapter 20 DNA Replication, Repair, and Recombination 1. How is DNA replicated? 2. Proteins involved in DNA replication in Ecoli. 3. The process of DNA replication 4. DNA replication in eukaryotes 5. Repair of damaged DNA 20.1 How is DNA replicated? A0002701.mov DNA replication requires unwinding of the DNA helix DNA replication is semiconservative DNA replication is bidirectional DNA replication is semidiscontinuous DNA replication requires unwinding of the DNA helix DNA gyrase ( topoisomerase II) Helicase A0255801.mov DNA replication is semiconservative DNA replication is bidirectional Autoradiograph of a replicating E. coli chromosome Electron micrograph of replicating DNA from an embryo of the fruit fly Drosophila melanogaster DNA replication is semidiscontinuous 20.2 Proteins involved in DNA replication in Ecoli v Topoisomerase and Helicase Topoisomerase (DNA gyrase) An enzyme that alters the supercoiling of a DNA molecule by cleaving a phosphodiester linkage in either one or both strands, rewinding in the DNA , and resealing the break. Helicase (DNA B) An enzyme that is involved in unwinding DNA. SSB Single-strand binding protein tetramer cover about 32 nucleotides of DNA binding of DNA is cooperative function ? Primase An enzyme in the primosome that catalyzes the synthesis of short pieces of RNA about 10 residues long. Theses oligonucleotides are the primers for synthesis of Okazaki fragments. DNA polymerase III 1 Ααalpha a:lf 阿尔法 2 Ββbeta bet 贝塔 3 Γγgamma ga:m 伽马 4 Δ δdelta delt 德尔塔 5 Ε εepsilon ep`silon 伊普西龙 6 Ζζzeta zat 截塔 7 Ηηeta eit 艾塔 8 Θ θthet θit 西塔 9 Ιιiot aiot 约塔 10 Κκkappa kap