19.1 Introduction 19.2 The nucleosome is the subunit of all chromatin 19.3 dNA is coiled in arrays of nucleosomes 19.4 Nucleosomes have a common structure 19.5 DNA structure varies on the nucleosomal surface 19.6 Supercoiling and the periodicity of DNA 19. The path of nucleosomes in the chromatin fiber 19.8 Organization of the histone octamer 19.9 Histones are modified 19 10 Reproduction of chromatin requires assembly of nucleosomes 19.11 Do nucleosomes lie at specific positions? 9 12 Are transcribed genes organized in nucleosomes? 19 13 Histone octamers are displaced by transcription 19 14 DNAase hypersensitive sites change chromatin structure 19.15 Domains define regions that contain active genes 19.16 Heterochromatin propagates from a nucleation event 19 17 Heterochromatin depends on interactions with histones 19.18 X chromosomes undergo global changes 19.19 Chromosome condensation is caused by condensins 19.20 Methylation is perpetuated by a maintenance methylase 19.21 Methylation is responsible for imprinting 19.22 Epigenetic effects can be inherited 19.23 Yeast prions show unusual inheritance 19.24 Prions cause diseases in mammal 消当19.1 Introduction 19.2 The nucleosome is the subunit of all chromatin 19.3 DNA is coiled in arrays of nucleosomes 19.4 Nucleosomes have a common structure 19.5 DNA structure varies on the nucleosomal surface 19.6 Supercoiling and the periodicity of DNA 19.7 The path of nucleosomes in the chromatin fiber 19.8 Organization of the histone octamer 19.9 Histones are modified 19.10 Reproduction of chromatin requires assembly of nucleosomes 19.11 Do nucleosomes lie at specific positions? 19.12 Are transcribed genes organized in nucleosomes? 19.13 Histone octamers are displaced by transcription 19.14 DNAase hypersensitive sites change chromatin structure 19.15 Domains define regions that contain active genes 19.16 Heterochromatin propagates from a nucleation event 19.17 Heterochromatin depends on interactions with histones 19.18 X chromosomes undergo global changes 19.19 Chromosome condensation is caused by condensins 19.20 Methylation is perpetuated by a maintenance methylase 19.21 Methylation is responsible for imprinting 19.22 Epigenetic effects can be inherited 19.23 Yeast prions show unusual inheritance 19.24 Prions cause diseases in mammals