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45 Cards in this Set
- Front
- Back
Plasma Membrane
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The selectively permeable surface membrane that encloses the cell contents and through which all materials entering or leaving must pass.
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Amphipathic Molecules
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A molecule containing both hydrophobic and hydrophilic regions.
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Fluid Mosaic Model
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The currently accepted model of the plasma membrane and other cell membranes in which protein molecules "float" in a fluid phospholipid bilayer.
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Integral Membrane Proteins
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A protein that is tightly associated with the lipid bilayer of a biological membrane.
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Transmembrane Proteins
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An integral protein that spans across the lipid bilayer.
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Peripheral Membrane Proteins
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A protein associated with one of the surfaces of a biological membrane.
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Glycoproteins
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A protein with covalently attached carbohydrates.
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Selectively Permeable Membrane
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A membrane that allows some substances to cross it more easily than others.
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Carrier Protein
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Proteins that changes in shape to bind to ions or molecules to move that molecule across the membrane.
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Carrier Mediated Transport
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Any form of transport across a membrane-bound transport protein with a binding site for a specific substance.
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Channel Proteins
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Proteins that form tunnels through the cell membrane.
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Porins
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Transmembrane proteins that allow various solutions or water to pass through membranes.
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Aquaporins
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Transmembrane proteins that function as gated water channels.
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Diffusion
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The net movement of particles from a region of higher concentration to a region of lower concentration.
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Concentration Gradient
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A difference in the concentration of a substance from one point to another.
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Dynamic Equilibrium
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The condition of a chemical reaction when the rate of change in one direction is exactly the same as the rate of change in the opposite direction.
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Osmosis
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The net movement of water by diffusion through a selectively permeable membrane from a region of higher concentration to a region of lower concentration.
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Osmotic Pressure
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The pressure that must be exerted on the hypertonic side of a selectively permeable membrane to prevent diffusion of water from the side containing pure water.
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Isotonic
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A solution that has identical concentrations of solute and the same osmotic pressure.
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Hypertonic
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A solution with an osmotic pressure greater than that of the solution it is being compared to.
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Hypotonic
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A solution with an osmotic pressure lower than that of the solution being compared.
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Turgor Pressure
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Hydrostatic pressure that develops within a walled cell when the osmotic pressure of the cell's contents is greater than the osmotic pressure of the surrounding fluid.
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Plasmolysis
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The shrinkage of cytoplasm and pulling away of the plasma membrane from the cell wall when a walled cell loses water.
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Facilitated Diffusion
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The passive transport of ions or molecules by a specific carrier protein in a membrane.
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Liposomes
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Artificial vesicles surrounded by a phospholipid bilayer.
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Active Transport
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Transport of a substance across a membrane that does not rely on the potential energy of a concentration gradient for the substance being transported; therefore requires an additional source of energy.
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Sodium-Potassium Pump
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Active transport system that transports sodium ions out of and potassium ions into cells.
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Uniporters
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Carrier proteins that transport a substance in one direction.
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Symporters
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Carrier proteins that move two types of substances in one direction.
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Antiporters
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Carrier proteins that move two substances in opposite directions.
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Cotransport System
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The active transport of a substance from a region of low concentration to a region of high concentration by coupling its transport to the transport of a substance down its concentration gradient.
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Exocytosis
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The active transport of materials in and out of the cell by fusion of cytoplasmic vesicles with the plasma membrane.
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Endocytosis
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The active transport of substances into the cell by formation of invaginated regions of the plasma membrane that pinch off and become cytoplasmic vesicles.
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Phagocytosis
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"cell eating"; a type of endocytosis by which certain cells engulf food particles, microorganisms, foreign matter, or other cells.
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Pinocytosis
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"cell drinking"; a type of endocytosis by which cells engulf and absorb droplets of liquids.
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Ligand
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A molecule that binds to a specific site in a receptor or other protein.
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Desmosomes
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Buttonlike plaques present on two opposing surfaces that hold cells together by means of protein filaments that span the intercellular space.
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Plasmodesmata
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Cytoplasmic channels connecting adjacent plant cells and allowing for movement of molecules and ions between cells.
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Desmotubule
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A narrow cylindrical structure in a plasmodesmata that runs through a channel and connects the smooth ER of two adjacent cells.
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Indirect Active Transport
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Type of transport in which two solutes are transported at the same time.
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Receptor-Mediated Endocytosis
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Specific receptors in coated pits along the plasma membrane bind ligands.
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Anchoring junctions
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They are found between cells that form a sheet of tissue; include desmosomes and adhering junctions.
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Adhering Junctions
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Junctions that are formed by cadherins that cement cells together.
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Tight Junctions
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Seal membranes of adjacent animal cells together preventing substances from moving through the spaces between cells.
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Gap Junction
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Form channels that allow communication between the cytoplasm of adjacent cells.
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