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membrane |
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membraneIn living things, a continuous layer, made up principally of fat molecules, that encloses a cell or organelles within a cell. Small molecules, such as water and sugars, can pass through the cell membrane by diffusion. Large molecules, such as proteins, are transported across the membrane via special channels, a process often involving energy input. The Golgi apparatus within the cell is thought to produce certain membranes. In cell organelles, enzymes may be attached to the membrane at specific positions, often alongside other enzymes involved in the same process, like workers at a conveyor belt. Thus membranes help to make cellular processes more efficient. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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While the ear of the former has an external opening, that of the latter is entirely and evenly covered over with a membrane, so as to be quite imperceptible from without. His eyes were half-filmed over by a growth of morbid membrane, and what was not yet covered shone red and irritated. The shells were a little open; the Captain came near and put his dagger between to prevent them from closing; then with his hand he raised the membrane with its fringed edges, which formed a cloak for the creature. |
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