Membrane Transport

active transport

molecules move across the plasma membrane against their concentration gradient.

facilitated diffusion

A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of

through facilitated diffusion or diffusion

Water crosses the plasma membrane

active transport

The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of


The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of