Here's why:
* Selective Permeability: The cell membrane is selectively permeable, meaning it allows some substances to pass through while blocking others. This is essential for maintaining the cell's internal environment and carrying out its functions.
* Phospholipid Bilayer: The cell membrane is composed of a phospholipid bilayer, which acts as a barrier between the inside and outside of the cell.
* Proteins: Embedded within the membrane are various proteins that play key roles in transport:
* Channel proteins: Act like tunnels, allowing specific molecules to pass through.
* Carrier proteins: Bind to specific molecules and transport them across the membrane.
* Receptor proteins: Bind to signaling molecules, triggering changes within the cell.
Through these mechanisms, the cell membrane carefully regulates what enters and exits the cell, ensuring its survival and proper functioning.
