Brownian movement - random mov't of molecules in biological systems
- occurs due to collisions between molecules
- molecules' mov't can't directly be seen, but mov't after collisions can be seen
diffusion - directional mov't of molecules down a gradient
- from areas of high concentration, heat, pressure to areas of low concentration, heat, pressure
- rate determined by steepness of gradient and characteristics of the molecules
- temperature/pressure usually constant in most biological systems
- selective (differentiable) permeability - ability of cell membranes to decide what moleules can pass through it; selects based on size, charge, solubility
- polar molecules - positive/negative charged areas
- nonpolar molecules - no local areas of charge
- small nonpolar molecules pass through the membrane most easily
- dialysis - separation of dissolved substances by using their unequal diffusions
osmosis - diffusion of water across a differentially permeable membrane
- follows rules of diffusion, except w/ water
- hypotonic - solution w/ lower solute concentration than surrounding environment
- hypertonic - solution w/ higher solute concentration than surrounding environment
- isotonic - 2 solutions w/ equal solute concentration
- water moves from hypotonic to hypertonic areas
- even in isotonic solutions, water still moves, but concentrations stay the same
water potential - effects of concentration/pressure from cell walls
- increased by high water concentration/pressure
- decreased by high solute concentration, low pressure
- water flows from areas of high water potential to areas of low water potential
lysis - destruction of cell by influx of water
- animal cells lack cell walls, bursts more easily than plant cells
- hemolysis - lysis of red blood cells
- crenation - shriveling of cells
- plasmolysis - shrinking of plant cytoplasm, where cell membrane pulls away from cell wall in plants
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