5染色体的分子结构 化学组成:1/3DNA,1/3 Histones and 1/3 Nonhistone ()Nucleosomes H2B H4 H2A H3 Linker DNa Linker dna
5 染色体的分子结构 化学组成：1/3 DNA,1/3 Histones and 1/3Nonhistons (1)Nucleosomes
细胞类别 核小体DNA含量(bp) 曲霉 154 酵母 165 链孢霉 170 鼠骨髓 192 鼠肝 198 鼠肾 196 鸡输卵管 196 雏鸡红细胞 207 海胆精子 241 Hela(培养) 183
细胞类别 核小体DNA含量(bp) 曲霉 154 酵母 165 链孢霉 170 鼠骨髓 192 鼠 肝 198 鼠肾 196 鸡输卵管 196 雏鸡红细胞 207 海胆精子 241 Hela(培养) 183
Histones abound in the chromatin of all eukaryotic cells TABLE Some Molecular Characteristics of the histone Proteins Found in Calf Thymus* Histone Basic/Amino Acid Molecular Weight Total Amino Acid Residues H1 54 23.000 224 H2A 14 13960 H2B 1.7 13,774 125 H 1.8 15,273 H4 11.236 102 Note the small size of the histones; in addition, their predominantly basic amino aad constitution ensures that they will be positively charged in physiological conditions. Nonhistones proteins have diverse functions
Nonhistones proteins have diverse functions Histones abound in the chromatin of all eukaryotic cells
gure Nonhistone proteins have diverse functions (a)Some nonhistone proteins form the chromosome scaffold. when the human chromosome in this picture was gently treated with detergents to remove the histones and some of the nonhistone proteins, a dark scaffold composed of some d the remaining nonhistone proteins, and in the shape of the two sister chromatids became visible. Loops of DNA freed by the detergent treatment surround the scaffold. (b)Some nonhistone proteins power chromosome movements along the spindle during cell division this figure, chromosomes are stained in blue and a nonhistone protein knowvn as CENP-E is stained in recl. CENP-E is located at the sister kinetochores of each duplicated chromosome and appears to play a major role in moving separated sister chromatics toward the spindle poles during anaphase