Figure 12A-3 Sedimentation Coefficients and Densities of Organelles, Macro molecules, and Viruses. A particle's 1.9 sedimentation coefficient, expressed in Svedberg units (S) indicates how rapidly it DNA sediments when subjected to a centrifugal Glycogen force. A particle's density (expressed in g/cm) determines how far it will move during Ribosomes and polysomes equilibrium density centrifugation Soluble protei Peroxisome Nuclei iruses Lysosomes Mitochondria Chloroplasts 1001000104 105 Sedimentation coefficient (S) (continued)
P505 RNA Polymera Ribosome EDNA
P505
Special techniques: Negative staining: for very small particulate materials, which collects little stain.( uranyl acetate, potassium phosphotungstate) Shadow casting: to evaporate heavy metal and deposit a metallic coat over the accessible surfaces of specimen. Heated filament is composed of platinum together with carbon Fr Freeze-fracture replication and Freeze etching rapidly freeze specimen at-150 C without fixative Freeze-fracture replication( shadow a casting heavy metal layer and then a carbon layer is deposited on the fracture surface, then the Freeze etching( a layer of ice can evaporate from the surface) and rapid-freeaing, deep-etching(-269oC)specimen is remove d
*Special techniques: N Negative staining: for very small particulate materials, which collects little stain. ( uranyl acetate, potassium phosphotungatate) Shadow casting: to evaporate heavy metal and deposit a metallic coat over the accessible surfaces of specimen. Heated filament is composed of platinum together with carbon . Fr Freeze-fracture replication and Freeze etching: rapidly freeze specimen at –150oC without fixative. Freeze-fracture replication ( shadow a casting heavymetal layer and then a carbon layer is deposited on the fracture surface, then the Freeze etching ( a layer of ice can evaporate from the surface) and rapid-freeaing, deep-etching(-269 oC)specimen is removed)
主要电镜制样技术 ●超薄切片技术用于电镜观察的样本制备示意图 ●鱼染色技术 Negative staining 染色背景,衬托出样品的精细结构 ●金属投影 冰冻蚀刻技术( Freeze etching)(技术示意图 冰冻断裂与蚀刻复型:主要用来观察膜断裂面 的蛋白质颗粒和膜表面结构。 快速冷冻深度蚀刻技术( quick freeze deep etching ●电镰三维重构技术 电子显微术、电子衍射与计算机图象处理相结合 而形成的具有重要应用前景的一门新技术。 电镜三维重构技术与X-射线晶体衍射技术及核磁 共振分析技术相结合,是当前结构生物学。 ( Structural Biology)—主要研究生物大分子空间结构及其 相互关系的主要实验手段
主要电镜制样技术 超薄切片技术 用于电镜观察的样本制备示意图 负染色技术（Negative staining） 染色背景，衬托出样品的精细结构 金属投影 冰冻蚀刻技术（Freeze etching） （技术示意图） 冰冻断裂与蚀刻复型：主要用来观察膜断裂面 的蛋白质颗粒和膜表面结构。 快速冷冻深度蚀刻技术（quick freeze deep etching） 电镜三维重构技术 电子显微术、电子衍射与计算机图象处理相结合 而形成的具有重要应用前景的一门新技术。 电镜三维重构技术与X-射线晶体衍射技术及核磁 共振分析技术相结合，是当前结构生物学。 （Structural Biology）——主要研究生物大分子空间结构及其 相互关系的主要实验手段
Figure 16 14 Examples of negatively stained and metal- dow casting with chromiun mh