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diffusion

movement of solute molecules from an area of greater concentration to an area of lesser concentration

a solution surrounding a cell is hypertonic is

it contains more nonpenetrating solute particles than the interior of the cell

passive processes

pressure differences drive the movement

active processes

ATP powers transport

filtration

occurs only across capillary walls

all molecules

possess energy and are in constant motion

molecules diffuse passively if

can dissolve in lipid portion of membrane

simple diffusion

unassisted diffusion of solutes through a differentially permeable membrane

facilitated diffusion

(passive) molecules transported with assistance of protein carrier molecules, small ions cross membrane by moving through water-filled protein channels

osmosis

flow of water across differentially permeable membrane; concentration of water is inversely related to the concentration of the solutes, cause changes in the volume of the compartments on either side of the membrane

hypertonic

contains more nonpenetrating solute particles than the interior of the cell; water moves down concentration gradient

hypotonic

contains fewer solute particles than interior of the cell; water moves down concentration gradient

hemolysis

cells burst as the water floods into them, leavings "ghosts"

active transport

requires carrier proteins; primarily driven by ATP or secondary driven by energy store; substances move against concentration gradient; some are amino acids and some sugars
sodium ions are ejected from the cell by this

vesicular transport

large particles and molecules transported across membrane

phagocytosis

membranous sac thus formed, phagosome, fused w/ lysosome and contents digested; mainly found among white blood cells and macrophages to help protect body from disease and cancer cells

molecular motion

-reflects the kinetic energy of molecules
-is random and erratic

velocity of molecular movement

-is lower in larger molecules
-increases with increasing temperature
-reflects kinetic energy

what single characteristic of the differentially permeable membranes in lab determine the substances that can pass through them

size of pores in dialysis sac

what other factors influence passage of substances through living membranes

size of molecules, polarity of molecules, concentration gradient

characterize passive processes

-include osmosis, simple diffusion, and filtration
-use hydrostatic pressure or molecular energy as the driving force
-account for the movement of fats and respiratory gases through the plasma membrane

characterize active processes

-may occur against concentration and/or electrical gradients
-explain solute pumping, phagocytosis, and pinocytosis
-move ions, amino acids, and some sugar across the plasma membranex

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