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31 Cards in this Set
- Front
- Back
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Selective Permeability |
Allows some substances to cross the plasma membrane more easily than others |
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Amphipathic |
Both a hydrophilic region and a hydrophobic region |
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Fluid Mosaic Model |
Membrane is a mosaic of protein molecules, bobbing in a fluid bilayer of phospholipids |
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Integral proteins |
penetrate the hydrophobic interior of the lipid bilayer |
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Transmembrane proteins |
Span the entire length of the membrane |
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Peripheral proteins |
Not embedded in the lipid bilayer; loosely bound to the surface of the membrane, often to exposed parts of integral proteins |
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Glycolipids |
Membrane carbohydrates covalently bonded to lipids |
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Glycoproteins |
Membrane carbohydrates covalently bonded to proteins |
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Transport proteins |
Hydrophlic substances avoid contact by passing through these. |
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Channel protein |
Has a hyrdophilic channel that certain molecules or ions use as a tunnel through the membrane |
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Aquaporins |
Channel proteins that facilitate the passage of water through the membrane |
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Carrier Proteins |
Transport proteins that hold onto their passengers and change shape to cross the membrane |
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Diffusion |
Movement of particles of any substance so that they spread out into available space |
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Concentration gradeitn |
Region along which the density of a chemical substance increases or decreases |
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Passive Transport |
Does not have to expend energy, high to low |
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Osmosis |
Diffusion of free water across a selectively permeable membrane |
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Hypotonic |
Water enters cell faster than it leaves and bursts |
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Hypertonic |
Cell loses water and shrivels |
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Isotonic |
No net movement of water |
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Facilitated Diffusion |
Polar molecules and ions diffuse passively with the help of transport proteins |
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Ion Channels |
Channel proteins that transport ions |
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Gated Channels |
Open or close in a response to a stimulus |
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Active Transport |
Pumping a solute across a membrane against its gradient expends energy in form of ATP |
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Sodium-Potassium Pump |
Exchanges Na+ for K+ across the membrane of animal cells |
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Elctrogenic Pump |
Transport protein that generates voltage across a membrane |
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Proton Pump |
Main electrogenic pump, actively transports protons out of the cell |
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Cotransport |
Couple the downhill diffusion of a solute to the uphill transport of a second substance against its own concentration gradient |
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Membrane Potential |
Voltage across a membrane, ranges from about -50mv to -200 |
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Eelctrochemical Gradient |
Combination of forces acting on an ion |
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Exocytosis |
Cell secretes certain molecules by the fusion of vesicles with the plasma membrane |
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Endocytosis |
Cell takes in molecules and particulate matter by forming new vesicles from plasma membrane |
