作业帮冰冻蚀刻有哪些类型?有什么区别?
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冰冻蚀刻有哪些类型?有什么区别?
冰冻蚀刻有哪些类型?
有什么区别?
冰冻蚀刻有哪些类型?有什么区别?
[编辑本段]冰冻蚀刻(freeze-etching)技术
是在冰冻断裂技术的基础上发展起来的更复杂的复型技术.如果将冰冻断裂的样品的温度稍微升高,让样品中的冰在真空中升华,而在表面上浮雕出细胞膜的超微结构.当大量的冰升华之后,对浮雕表面进行铂-碳复型,并在腐蚀性溶液中除去生物材料, 复型经重蒸水多次清洗后,置于载网上作电镜观察.
冰冻蚀刻（freeze-etching）亦称冰冻断裂（freeze-fracture）.标本置于-100˚C的干冰或-196˚C的液氮中,进行冰冻.然后用冷刀骤然将标本断开,升温后,冰在真空条件下迅即升华,暴露出断面结构,称为蚀刻（etching）.蚀刻后,向断面以45度角喷涂一层蒸汽铂,再以90度角喷涂一层碳,加强反差和强度.然后用次氯酸钠溶液消化样品,把碳和铂的膜剥下来,此膜即为复膜（replica）.复膜显示出了标本蚀刻面的形态,在电镜下得到的影像即代表标本中细胞断裂面处的结构.
freeze-fracture replicaDefinition:
A technique used to look at membranes that reveal the pattern of integral membrane proteins.
General outline of technique:1. Cells are qui...
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freeze-fracture replicaDefinition:
A technique used to look at membranes that reveal the pattern of integral membrane proteins.
General outline of technique:1. Cells are quickly frozen in liquid nitrogen (196C), which immobilizes cell components instantly.
2. Block of frozen cells is fractured. This fracture is irregular and occures along lines of weakness like the plasma membrane or surfaces of
organelles.3. Surface ice is removed by a vacuum (freeze etching)
4. A thin layer of carbon is evaporated vertically onto the surface to produce a carbon replica.
5. Surface is shadowed with a platinum vapor.
6. Organic material is digested away by acid, leaving a replica.
7. Carbon-metal replica is put on a grid and examined by a transmission electron microscope.
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