Facilitated Diffusion is... Still diffusion so: Passive No energy Molecules move from high to low concentration Different than simple diffusion because: Molecules move through a channel protein in the membrane Used for small charged molecules (ions)

PHOSPHOLIPID BILAYER MUST BE... studded with channel proteins to allow facilitated diffusion to occur. Channels are holes through a protein with very narrow diameter. The diameter and chemical properties of the proteins ensure that only one type of particle can pass through. For example, sodium ions or potassium ions, but not both. Example channel created by a hole surrounded by protein

EXAMPLE The CFTR Channel moves chloride ions out of the cell. People with cystic fibrosis have a mutation that causes the CFTR channel to have the wrong shape and as a result the channel can not move the chloride ions. The ions build up in the cell. The consequences are huge.

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