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15 Cards in this Set
- Front
- Back
selective permeability
or semipermeable |
membrane is a barrier allowing some substances to pass through more readily than others
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lipid bilayer permeability
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permeable to nonn-polar uncharged molecules (0,C02, steroids)
slightly permeable to H2O & urea (leak through as lipids flip-flop) channels & transporters provide selective permeability |
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2 criterion used to classify transport processes
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1) mediation
2) Energy used (active/passive) |
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mediated transport
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involves assistance of a transporter protein
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non-mediated transport
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does not require a transporter protein
(lipid layer/channel diffusion) |
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Active transport
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needs additional energy (usually ATP) to move up a concentration gradient
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Passive transport
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uses chemical's kinetic energy to move down a concentration gradient
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concentration gradient
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the difference in the concentration of a chemical from one place or another
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electrical gradient
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the difference in electrical charges in two regions;
it occurs across the plasma membrane so it is termed MEMBRANE POTENTIAL |
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electrochemical gradient
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combined influence of concentation gradient and membrane potential
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diffusion
(in a solution) |
passive process
random mixing of particles in a solution solute moves down it's concentration gradient in the solvent until equilibrium is reached |
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solute
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dissolved substance
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solvent
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liquid that does the dissolving
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equilibrium
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particles are evenly distributed in the solution
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Laws of Diffusion
(factors that influence diffusion across a membrane) |
1) steepness of concentration gradient
2) temperature 3) mass of the diffusing substance 4) surface area 5) diffusion distance |