BIOL 206 Chapter Notes - Chapter 6.4: Eukaryote, Aquaporin, Glucose Transporter
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The substances diffuse according to their concentration gradients but their diffusion is aided by channel proteins or carriers: ion channels are example of channel protein. Hydrophilic pore that allows a particular ion to move through its center. Just as fence may have gate that can be opened or closed, most ion channels are gatedthey can be opened or closed to ion passage. A gated channel opens when a stimulus causes a change in the three d shape of a channel. In some cases the stimulus is the binding of a chemical signal or ligand. Channels are controlled in this way are called liganagated channels. Gaps are enclosed by toms that are exactly the right size so that when k ion approaches the opening, it is more attracted to the oxygen atoms than those of the water molecules. It sheds its water shell and passes through the channel.