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建立人际资源圈History_Of_Cell_Membrane
2013-11-13 来源: 类别: 更多范文
History Of Cell Membrane
In the early stages of the twentieth century, little was known about cell membranes. Until the early 1950s, the biological cell membrane was rarely mentioned in scientific literature. It was recognised that something was probably there, but hardly anything about it was known. Considering the lack of technical equipment available a century ago, scientists such as Charles Overton and Edwin Gorter were not only exploring new territory in looking at the properties of cell membranes, but laying the way for future cell biologists. Scientists had to wait another fifty years for the discovery of the electron microscope, let alone seventy years for the advent of freeze fracturing techniques.
Nageli and Cramer in 1855 had already suggested that biological cells are separated from their environment by a membrane possessing special characteristics, and in 1900 Overton performed some simple but classical experiments which proposed that cell membranes were composed of lipids (1). By measuring the permeability of various compounds across the membrane of a frog muscle, Overton found some interesting results. He observed that lipophilic molecules (molecules attracted to fat solvents) could easily cross this cell membrane, however larger lipid insoluble molecules could not. He also observed that small polar molecules could
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