Here's why:
* Selective Permeability: The cell membrane is selectively permeable, meaning it allows some substances to pass through while blocking others. This is crucial for maintaining the cell's internal environment and carrying out its functions.
* Structure: The cell membrane is composed of a phospholipid bilayer with embedded proteins. This structure provides a barrier between the inside and outside of the cell.
* Transport Mechanisms: The cell membrane utilizes various transport mechanisms to move substances across its surface. These include:
* Passive transport: Diffusion, osmosis, and facilitated diffusion, which do not require energy.
* Active transport: Requires energy (usually from ATP) to move substances against their concentration gradient.
In short, the cell membrane acts as a gatekeeper, carefully controlling the movement of molecules and ions into and out of the cell, ensuring the cell's survival and proper functioning.
