When substance are moving into or out of the cell, some substances are able to move directly through the phospholipid bilayer. But in order for ions to pass through the plasma membrane, they must go through a transport protein that is embedded in the phospholipid bilayer.
We’ll be looking at two broad categories of methods that substances use to pass through the plasma membrane: passive transport and active transport.
For passive transport mechanisms, molecules use their own energy to move through the membrane. (We’ll discuss this more detail later.)
But active transport mechanisms require the cell to use energy and a transport protein is use to move the substance from one side of the plasma membrane to the opposite side.
Here’s a video that expains the difference passive and active transport