The cell membrane is made of ______? 

Key Points

• The cell membrane, also called the plasma membrane, is a thin, flexible layer that encloses the cell and separates its internal environment from the external environment.
• It is composed of a variety of components, including lipids, proteins, and carbohydrates, but the most abundant and important component is the phospholipid bilayer.
• The phospholipid bilayer is composed of two layers of phospholipid molecules, which have a polar, hydrophilic head and a nonpolar, hydrophobic tail.
• The hydrophobic tails face each other, creating a barrier to the movement of hydrophilic molecules such as ions and water, while the hydrophilic heads face outward, interacting with the aqueous environments inside and outside the cell.

Additional Information

• Proteins are also an important component of the cell membrane, and they are embedded in the phospholipid bilayer or attached to its surface. These proteins serve a variety of functions, including transporting molecules across the membrane, acting as receptors for chemical signals, and providing structural support.
• Phosphoproteins: These are proteins that have been modified by the addition of phosphate groups. While some membrane proteins may be phosphoproteins, the membrane itself is not composed of phosphoprotein.
• Fat: While lipids are an important component of the cell membrane, they are specifically phospholipids, not fats. Fats, or triglycerides, are a type of lipid that is used primarily for energy storage, not membrane structure.