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Consider the main processes in which substances pass through the plasma membrane.
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| Submitted: Wed Mar 03 2004
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There are many ways in which different substances can move in and out of the plasma membrane of a cell. A reason for the movement of substances in and out of cells is the structure of the cell membrane, which is about 7nm thick and is made of a phospholipid bilayer that allows molecules to pass. I am going to consider the main processes in which substances pass through the plasma membrane. Firstly, I will look at simple diffusion. Diffusion is the random movement of particles in a gas or liquid down a concentration gradient from a region of high concentration to low concentration*. This is the primary method by which substances are transported. The molecules are soluble in lipids and diffuse through the membrane when they collide into its bilayer. Simple diffusion is effected by many factors. For example, the larger the surface area the more efficient diffusion is. Other factors...
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