ASCI 112 Study Guide - Quiz Guide: Phospholipid, Biological Membrane, Osmosis
Document Summary
Selective physical & chemical barrier deciding what comes into and leaves cell=selectively permeable. (cid:1445)gatekeeper(cid:1446) regulates passage of gases, nutrients, and wastes between internal and external environments of cell. Embedded in the plasma membrane a diverse range of proteins which help with passages of molecules. Lipids are majority of structure, but proteins give membrane function. Carbohydrates found on the surface of plasma membranes (attached to lipid: glycolipids or proteins: glycoproteins) help contribute to cell-cell recognition, communication, and intracellular adhesion. Cholesterol helps maintain the integrity (stability) of these membranes, and plays a role in facilitating cell signaling-meaning the ability of your cells to communicate with each. Movement of water and nutrients into cell or elimination of wastes out of cell essential for survival. Occurs across a biological membrane in one of three ways. Net movement of molecules from area of higher concentration to area of lower concentration=diffusion. Molecules diffuse down a concentration gradient from higher to lower concentrations.
