PHY2011 Study Guide - Final Guide: Active Transport, Integral Membrane Protein, Lipid Bilayer
14 Sep 2013
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Document Summary
Cell and membrane physiology: describe the structure of a biological membrane. The cell membrane is a biological membrane that seperates the interior of all cells from the outside environment. The cell membrane is a selectively permeable membrane to ions and organic molecules and controls the movement of substances into and out of cells. The cell membrane is not rigid, but a fluid structure. The fluidity of the cell is due to the phospholipid molecules and proteins moving within the lateral plane of the bilayer. The cell membrane"s fluidity depends on the lipid composition, amount of cholesterol and temperature. The lipid composition and amount of cholesterol varies across the membrane, and between the two surfaces of the membrane. There are no covalent bonds between phospholipids or between phospholipids and proteins. Due to this, the molecules can move independently, in the plane of the membrane. Therefore, there is a lot of lateral movement of the phospholipids.
