What are the design and characteristics of channel protein molecules?
The other special proteins in cell membranes are known as channels (including water channels and various ion channels). Channel proteins have water-filled passageways that link the inside and the outside of the cell. Channel proteins are physically more like pores. They are special proteins that have pore-like openings in the middle of them to allow certain types of molecules to go through them. For example, water channels have very small openings so that only very small water molecules can go through. Ion channels discriminate among various types of ions by having different sized openings and different electrical charges lining the openings. Channel proteins also exhibit selectivity and competition due to the characteristics of the inside of the channel and the entrances and exits to the channel. In addition, channel proteins exhibit saturation because they can be so full of the water or ion molecules that molecules need to go single file through the channel. Thus in order for one mol
