Diffusion
- Created by: Sophie Gibbons
- Created on: 06-01-13 14:06
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- Diffusion
- The movement of molecules in or out of a cell from a region of low concentration to a region of high concentration using energy and carrier molecules.
- Passive process
- Factors affecting rate of diffusion
- Concentration gradient - the greater the difference in concentration the greater the rate of diffusion.
- Surface area - the greater the surface area the greater the rate of diffusion.
- Thickness - the thinner the surface the greater rate of diffusion and pathway is short.
- Diffusion is proportional to surface area x difference in concentration / length of diffusion pathway.
- Facilitated diffusion
- Passive
- Use channel and carrier proteins.
- Occurs along plasma membrane.
- Proteins act as channels for the passage of water soluble molecules.
- Molecules bind to carrier protein causing them to change shape releasing the molecules at the other side.
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