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movement of a substance from an are of high concentration to an are of lower concentration caused by the random motion of particles
transport protein that binds to a specific substance on one side of the cell membrane, carry the substance across the cell membrane, and release it on the other side
passive transport because it moves substances down their concentration gradient without using the cell's energy
the transport of a substance across the cel membrane against its concentration gradient
sodium potassium pump
transports three sodium ions out of a cell and two potassium ions into the cell
protein that binds to a specific signal molecule enabling the cell to respond to the signal molecule
What needs to happen between cells during communication
signal molecules that bind to receptor proteins on cells
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