武汉大学生命科学学院：《分子生物学》（英文版）Part II：Maintenance of the Genome CHAPTER10 Homologous recombination at the molecular level

Molecular biology of the Gene 5/E - Watson et al. ( 2004) Part l: chemistry and genetics Part l: Maintenance of the Genome Part l: Expression of the Genome Part IV: Regulation Part v: Methods 3/29/05 刻博来字 Wuhan Universit

Molecular Biology of the Gene, 5/E --- Watson et al. (2004) Part I: Chemistry and Genetics Part II: Maintenance of the Genome Part III: Expression of the Genome Part IV: Regulation Part V: Methods 3/29/05

Part ll: Maintenance of the genome Dedicated to the structure of DNa and the processes that propagate, maintain and alter it from one cell generation to the next @博共字 Wuhan University

Part II: Maintenance of the Genome Dedicated to the structure of DNA and the processes that propagate, maintain and alter it from one cell generation to the next

Ch 6: The structures of dna and rna Ch 7: Chromosomes, chromatins and the nucleosome Ch 8: The replication of DNA Ch 9: The mutability and repair of DNA Ch 10: Homologous recombination at the molecular level Ch 11: Site-specific recombination and transposition of DNA 3/29/05

Ch 6: The structures of DNA and RNA Ch 7: Chromosomes, chromatins and the nucleosome Ch 8: The replication of DNA Ch 9: The mutability and repair of DNA Ch 10: Homologous recombination at the molecular level Ch 11: Site-specific recombination and transposition of DNA 3/29/05

Different changes of DNa sequences Listen to the nature Mutation is bad and naturally repaired thus it could not be responsible for biodiversity. Recombination is good and naturally promoted; it is responsible for diversity inside of species Transposition is different from mutation and recombination because (1) producing mechanism is different: (2) no mechanism to correct it; 3) existing in nature in a well-controlled manner(10-5). Not repaired but controlled

Different changes of DNA sequences Listen to the nature ◼ Mutation is bad and naturally repaired, thus it could not be responsible for biodiversity. ◼ Recombination is good and naturally promoted; it is responsible for diversity inside of species. ◼ Transposition is different from mutation and recombination because (1) producing mechanism is different; (2) no mechanism to correct it; (3) existing in nature in a well-controlled manner (10-5). Not repaired but controlled

● Molecular Biology course CHAPTER 10 Homologous recombination at the molecular level @劣博字 Wuhan Universit

CHAPTER 10 Homologous recombination at the molecular level •Molecular Biology Course

All dNA is recombinant dna a Genetic exchange works constantly to blend and rearrange chromosomes, most obviously during meiosis, when homologous chromosomes pair prior to the first nuclear division a During this pairing, genetic exchange between the chromosomes occurs. this exchange, classically termed crossing over, is one of the results of homologous recombination

◼ All DNA is recombinant DNA. ◼ Genetic exchange works constantly to blend and rearrange chromosomes, most obviously during meiosis, when homologous chromosomes pair prior to the first nuclear division. ◼ During this pairing, genetic exchange between the chromosomes occurs. This exchange, classically termed crossing over, is one of the results of homologous recombination

OUTLINE 1. Models for Homologous Recombination(two models*x 2. Homologous Recombination Protein Machines(RecBCD pathway* xK 3. Homologous Recombination in Eukaryotes(meiosis recombination proteins) 4. Mating-Type Switching(a gene conversion event) 5. Genetic Consequences of the Mechanism of Homologous Recombination(exchange or ConversIon

OUTLINE 1. Models for Homologous Recombination (two models)** 2. Homologous Recombination Protein Machines (RecBCD pathway)** 3. Homologous Recombination in Eukaryotes (meiosis recombination, proteins) 4. Mating-Type Switching (a gene conversion event) 5. Genetic Consequences of the Mechanism of Homologous Recombination (exchange or conversion)

CHAPTER 10 Homologous recombination at the molecular level Topic 1: Models for Homologous Recombination 1 Holliday model( Holliday模型) 2. Double-strand break ( dsB) repair model(双链断裂修复模型) 劣溪字 Wuhan University

Topic 1: Models for Homologous Recombination 1.Holliday model (Holliday模型) 2.Double-strand break (DSB) repair model (双链断裂修复模型) CHAPTER 10 Homologous recombination at the molecular level

Key steps shared by different models Alignment(结盟) of two homologous DNA molecules Introduction of breaks in the dna Formation of initial short regions of base pairing between the two recombining DNA molecules, strand invasion Movement of the Holliday junction branch migration >Cleavage of the holliday junction resolution

➢ Alignment (结盟) of two homologous DNA molecules. ➢ Introduction of breaks in the DNA ➢ Formation of initial short regions of base pairing between the two recombining DNA molecules: strand invasion ➢ Movement of the Holliday junction: branch migration ➢ Cleavage of the Holliday junction: resolution Key steps shared by different models

The holliday model illustrates key steps in homologous recombination The Holliday model very well illustrates the dna strand invasion branch migration, and Holliday junction resolution processes central to homologous recombination Watch the animation for details!

The Holliday model very well illustrates the DNA strand invasion, branch migration, and Holliday junction resolution processes central to homologous recombination. The Holliday model illustrates key steps in homologous recombination Watch the animation for details!