diffusion.docx - Introduction Molecules are constantly in...

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Introduction Molecules are constantly in motion due to the kinetic energy present in every atom. This energy results in the net movement of molecules from areas of high concentration to areas of low concentration, a process called diffusion . If uninhibited, this net movement will continue until equilibrium is reached and the molecules are uniformly distributed. Once equilibrium is achieved, molecules will continue to move in each direction at an equal rate. Diffusion A solution contains two or more substances ( solutes ) that have been dissolved by a solvent. In the context of a cell, the intracellular and extracellular fluids are the solvents which contain dissolved material (solutes). The rate of diffusion depends on membrane characteristics, size of the solute, and molecular polarity. Because the medium will not change in a biological system, the diffusion rate is usually dictated by molecular characteristics of the solute. Small, non-polar molecules exhibit a higher rate of diffusion than large, charged ones. Diffusion Factors The direction of diffusion depends on concentration gradients, heat, and pressure. The concentration
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