Explain the function and structure of …

The outer boundary of the cell is called the plasma membrane. The cytoplasm lies inside it. It is a living, thin, delicate, elastic, selectively permeable membrane.

Functions:

1. It separates the contents of the cell from its external environment.
2. The plasma membrane allows or permits the entry and exit of some materials in and out of the cell.
3. It also prevents movement of some other materials.

The cell membrane is called a selectively permeable membrane because it permits the entry and exit of some materials in the cell.

The plasma membrane is flexible and is made up of organic molecules called lipids and proteins. According to fluid mosaic model, plasma membrane is made up of a bilayer of phospholipids. There are two types of protein molecules: Intrinsic Proteins, which completely covers the lipid bilayer and Extrinsic Proteins, which occur either on the outer surface or on the inner surface of the lipid membrane.

The fluid mosaic membrane has been described as “a number of protein icebergs floating in the sea of lipids”.