The Cell Membrane

Cell Membrane Function

• The cell's plasma membrane acts as a barrier that selectively controls what enters and exits the cell.

Cell Membrane Composition

• The cell membrane is composed primarily of a phospholipid bilayer.
• The bilayer consists of two layers of phospholipids, with their hydrophilic (water-loving) heads facing the outside and inside of the cell, and their hydrophobic (water-fearing) tails facing each other in the middle.

Phospholipid Arrangement

• The phospholipids in the cell membrane are arranged in a bilayer structure.
• The hydrophilic heads of the phospholipids face the watery environment both inside and outside the cell.
• The hydrophobic tails of the phospholipids face each other in the middle of the membrane.

Embedded Proteins

• Proteins are embedded within the phospholipid bilayer.
• These proteins have various functions, including transporting molecules across the membrane, acting as receptors for signaling molecules, and providing structural support.

Permeability

• Small, nonpolar molecules (like oxygen and carbon dioxide) can easily pass through the cell membrane.
• Larger, polar molecules (like glucose and ions) need help from transport proteins to cross the membrane.

Test your knowledge on the structure and function of the cell membrane in this quiz. Learn about the phospholipids, proteins, and organelles that make up this important boundary of the cell.