分子生物学sectionD课件.ppt

1. Cell cycle Interphase 间期: G1 + S + G2 (G0) M phase (mitosis 有丝分裂): Prophase 前期 metaphase 中期 anaphase 后期 telophase 末期 2. Mitotic chromosome D3 Eukaryotic Chromosomal Structure Mitotic spindle Mitotic chromosome at metaphase Centromere 着丝粒 Telomere Nuclear matrix 核基质 Loops of 30nm fiber Sister chromatid 姊妹染色单体 Chromatid 染色单体 Kinetochore动粒 Centromere: 着丝粒, a region of chromosome where two sister chromatids are joined at metaphase. Kinetochore: 动粒, a protein complex attaching microtubules of mitotic spindle (纺锤体) Centrosome:中心体,where microbules grow out. With 2 centrioles. Centrioles :细胞中心粒,: 9 sets of triplet microtubles arranged in a ring Mitotic chromosome - centromere Yeast centromere Mammalian cells: much longer, flanked by satellite DNA (卫星DNA) A loop forms at the end of chromosomal DNA Mitotic chromosome - Telomere: end of chromosome Telomere Telomerase D3 Eukaryotic Chromosomal Structure Repeat sequence: tetrahymena(四膜虫)- TTGGGG; human- TTAGGG 3. Interphase chromosomes Chromatin 染色质 = Euchromatin 常染色质+ Heterochromatin 异染色质 Heterochromatin: Still highly condensed (visible under LM) Transcriptionally inactive Repeated satellite DNA close to the centromeres Whole chromosome e.g. one X chromosome in mammals Euchromatin: More diffuse. Consisting of 30nm fiber (inactive), beads-on-a-string, and active transcrption region depleted of nucleosome. Only a portion (~10%) of euchromatin is transcriptionally active. DNase I hypersensitivity(超敏性): DNase I cuts the backbone of DNA unless protected by bound protein. Short regions of DNase I hypersensitivity: 30 nm fiber is interrupted by the binding of a sequence-specific regulatory protein Longer regions of DNase I hypersensitivity: where transcription is taking place. Euchromatin: Histone variants and modification: (组蛋白变异体和修饰) The major mechanisms for the condensing and decondensing of chromatin operate directly throug