Cell Membrane

The cell membrane is a phospholipid bilayer that surrounds the cell.
Cells have a selectively permiable membrane.
The cell membrane is a phospholipid bilayer which consists of the hydrophilic heads and the hydrophobic tails.

• Hydrophobic tails are fatty acid and tucked inside the membrane sheilded from the water. The tails play the key role in makeing selective barrier.
• Hydrophilic heads are the outer part of the bilayer because they are "water loving" they determine the semi-permiability of the cell membrane by letting materials pass through without the water.

The membrane's purpose is to regulate the traffic of molecules in and out of the cell.
There are two ways for molecules to be transported in and out the cell passive and active transport.

• Passive Transport - When materials pass through the cell without requireing any energy from the cell.
• Active Transport - When a cell uses energy to move molecules across a membrane.

The cell uses vesicles, which are small mambrane sacs to transport products into, out of, and within the cell.
The process of material exiting the cell is called exocytosis, while material being brought into the cell is called endocytosis