A thin structure that completely surrounds the cell as a “skin.” They may be seen with the aid of an electron microscope. The entire membrane appears to be about 100 Angstroms (\u00c5; 0.1 \u03bcm) thick and is composed of two dark lines each about 30 A thick which are, however, separated by a lighter area. This trilaminar “sandwich” structure is referred to as the unit membrane. The plasma membrane is composed of lipoidal (fat-like) material in which proteins and protein complexes and whole functional systems are embedded. In the plasma membrane are incorporated such energy-dependent transport systems as Na+ and K+ transporting AT-Pase and amino acid transport systems. Besides the cell, membranes surround such systems as the endoplasmic reticulum, vacuoles, lysosomes, golgi bodies, mitochondria, chloroplasts, and the nucleus, to mention just a few. The plasma membrane and membranes in general function in part as a permeability barrier to the free movement of substances between the inside and exterior of the cell or organelles that they surround.<\/p>\n
The membrane that surrounds the cell. It regulates the passage of substances into and out of the cell.<\/p>\n
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A thin structure that completely surrounds the cell as a “skin.” They may be seen with the aid of an electron microscope. The entire membrane appears to be about 100 Angstroms (\u00c5; 0.1 \u03bcm) thick and is composed of two dark lines each about 30 A thick which are, however, separated by a lighter area. […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-38878","post","type-post","status-publish","format-standard","hentry","category-p"],"yoast_head":"\n