2 um
放射环染色体的形成 每圈碱基对包装比 棵露DNA ∞∞∞∞∞∞x)2mn10bp 10nm 10mm串珠 e 6个核小体/圈 30nm螺线管 40士 50圈/环 60000b 基质 18个环 基质 0.84m 1.1×105b+1.2×10 微带 (底面观 堆积 30nm 微带 染色体 (侧面观 18环/微带1.2×10° 图2-55染色体构建的骨架-放射环模型(引自K.J. Pienta等)
(2) The structure and function of nucleosome (3)Higher orders of chromatin organisation 3) Mitotic chromosome Mitotic chromosome structure. chromatid primary constriction, q/p, p/ p+q, secondary constriction, nucleolar organizer. satiate Element structures Replicating sequence Centromeres( Containing 170 bp long a-satellite DNA x 2, 000-30.000) and kinetochore Telomere human C-G rich, human TTAGGG/AATCCC repeats x several thousand times telomerase 4)Karyotype and chromosome banding 5)Special chromosome Polytene chromosome Lampbrush chromosome
(2) The structure and function of nucleosome (3) Higher orders of chromatin organisation 3) Mitotic chromosome Mitotic chromosome structure, chromatid, primary constriction, q / p, p / p+q, secondary constriction, nucleolar organizer. satilate Element structures: Replicating sequence Centromeres ( Containing 170 bp long a-satellite DNA x 2,000-30,000) and kinetochore Telomere human C-G rich, human: TTAGGG/AATCCC repeats x several thousand times telomerase 4) Karyotype and chromosome banding 5) Special chromosome Polytene chromosome Lampbrush chromosome
次、1- Nucleosome Nucleosomes (beads on a stnng) 30 nm (c) Looped domains 700nm (e) Highly condensed, duplicated chromosome of dividing cell Figure 16-21 Levels of Chromatin Packing. These diagrams and fiber (e) Looped domains of 30-nm fibers, visible in the TEMhe TEMs show a current model for progressive stages of DNA coiling and (d) Heterochromatin, highly folded chromatin that is visibie as discret (a)Beads on a string. an extended configuration of nucleosome spots even in interphase cells. (e)A replicated chromosome(two formed by the association of DNA with four types of histones.(b)The ttached chromatids) from a dividing call, with all the DNA of the 30-nm chromatin fiber, shown here as a tightly packed collection of chromosome in the form of very highly compacted heterochromatin nucleosomes. The fifth histone, H1, may be located in the interor of t
Figure 12.17 Each mitotic chromosome has a centromere warhnce cite is marked hv a distinct indentation Scanning elec-