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MEMBRANE STRUCTURE AND TRANSPORT – Week 5 Plasma Membrane A ________________________ membrane that surrounds the cytoplasm of a cell and Separates the contents of the cell from the outside environment and Regulates what ____________________________ the cell. Fluid Mosaic Model A model that describes the cell membrane as a flexible mosaic composed of embedded __________________ dispersed in a fluid ______________________________. Membrane Structure The membrane structure is composed of: o A Phospholipid bi-layer Made of amphiphatic molecules, meaning the molecules have both a _____________________ and ______________________ portion. o Steroid Cholesterol Helps _____________________ phospholipids and affects _____________________. o Carbohydrates Used for ___________________________. Membrane Function To ___________________________ transport IN and OUT of the cell: Simple Diffusion, Osmosis, Active Transport, Endocytosis/Exocytosis Adhesion Cell Communication Simple Diffusion – “Down the CONCENTRATION GRADIENT” The movement of molecules from an area of their ______________________ concentration to an area of their __________________________ concentration. Passive Transport o Diffusion across a biological membrane with NO expenditure of energy. At Equilibrium o Particles are in _______________________ motion. Osmosis* A special kind of passive transport. Diffusion of water through a semi-permeable membrane from an area of the highest H2O concentration to an area of the lowest H2O concentration. Tonicity: The relative solute concentration of one solution compared to another solution. H20 moves from the HYPOTONIC --> HYPERTONIC solution. o Hypotonic: ____________________ solute concentration. o Hypertonic: ____________________ solute concentration. o Isotonic: Solutions with _____________________ solute concentrations. Osmosis & Tonicity In osmosis, the solvent, typically H2O, moves from the ______________________ solution to the ______________________ solution. Cell Physiology & Tonicity Plant cells are surrounded by a rigid cell well, Animal cells are not. Lysed (blood cell): o When placed in a hypotonic solution, the blood cell will ________________ due to intake of water. Shriveled (blood cell): o When placed in a hypertonic solution, the blood cell will ________________ due to loss of water. Turgid (plant cell): o Hypotonic solution fills vacuoles with water and develops a turgid pressure. Flaccid (plant cell): o Isotonic solution, cell with neither gain nor lose water. Plasmolyzed (plant cell): o Hypertonic solution, vacuoles will lose water and the cytoplasm with shrink (plasmolysis). Facilitated Diffusion Passive Transport: ___________________ expenditure of energy Movement of particles (ions and polar molecules) down a concentration gradient via a _____________________________ that is embedded in a plasma membrane. Active Transport Requires expenditure of energy in the form of _________________________. Movement of solutes _______________________ the concentration gradient. Requires a transport protein. Selective Permeability Simple Diffusion Facilitated Diffusion Active Transport Endocytosis The movement of materials _________________ a cell via membranous vesicles. o Phagocytosis Cell “Eating” o Pinocytosis Cell “__________________________” Exocytosis The movement of materials ________________ of a cell via membranous vesicles