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Biology test 2
Term | Definition |
---|---|
Plasma membrane | outer boundary of the cell, 5-10 nm thick |
Cell wall | Mostly mechanical/protective role--provides support (strength and rigidity) to cell, and some filtering capacity. Found in plants, fungi, bacteria and archaea |
Cell membrane | In all cells; semi-permeable barrier that contains the cell cytoplasm, controls movement of substances in and out of cell. |
Compartmentalization | Membranes form continuous sheets that enclose specific intracellular compartments -- allowing specialized activities to proceed w/o extracellular interference |
Scaffolding (for biochemical activities) | membranes provide a framework that organizes enzymes for effective interaction-- b/c membranes are compartments themselves, as long as reactants are in solution, positions cant be stabilized and interactions depend on random collisions |
Selectively permeable barrier | membranes allow regulated exchange of substances between compartments-- gated barrier that promotes movement of select elements into and out of the cell |
Transporting solutes | membrane proteins facilitate the movement of substances between compartments-- physically transports the substances from low concentration of solute to high concentration of solutes |
responding to external signals: membra e |