Temperature and the Rate of Diffusion

Temperature and the Rate of Diffusion - Membranes are...

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Temperature and the Rate of Diffusion Molecules, atoms, and ions normally move about in an irregular fashion called Brownian motion. As the particles move about, they collide with one another producing a random zig-zag movement as illustrated by the applet below. http://www.aip.org/history/einstein/brownian.htm Larger particles move slower, due to their larger mass and may be influenced by numerous collisions with many nearby smaller particles. Smaller particles move faster. The overall energy of movement is proportional to the square root of the temperature. Hotter particles move faster because they have more energy. The rate of diffusion increases as temperature increases because the particles move faster. As temperature increases, the collisions among particles become more energetic, causing particles to move from areas of higher concentration to lower concentration at a faster rate.
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Unformatted text preview: Membranes are Differentially Permeable The plasma membrane is differentially permeable because some particles can pass through, others cannot. It can control the extent to which certain substances pass through. Nonpolar molecules pass through cell membranes more readily than polar molecules because the center of the lipid bilayer (the fatty acid tails) is nonpolar and does not readily interact with polar molecules. The following substances can pass through the cell membrane: Nonpolar molecules (example: lipids) Small polar molecules such as water The following substances cannot pass through the cell membrane: Ions and charged molecules (example: salts dissolved in water) Large polar molecules (example: glucose) Macromolecules...
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.

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