Summary:
- The plasma membrane (also known as the cell membrane) forms a barrier between the cytoplasm inside the cell and the environment outside the cell.
- It allows only certain substances to pass through, while keeping others in or out.
- To understand how the plasma membrane controls what crosses into or out of the cell, you need to know its composition.
- The plasma membrane is composed mainly of phospholipids, which consist of fatty acids and alcohol.
- As shown in the Figure below, each phospholIPid molecule has a head and two tails.
- The head “loves” water (hydrophilic) and the tails “hate’ water (Hydrophobic)