Profile
Settings
Refer your friends
Sign out
Answer: The cell membrane, also known as the plasma membrane, is a thin membrane that lines every live cell and separates it from its surroundings.
The cell membrane has two purposes:
- first, it as a barrier that keeps cell constituents in and undesired substances out, and
- second, as a gate that allows needed nutrients to enter the cell and waste products to exit
Cell membranes are primarily composed of fatty acid-based lipids and proteins.
The plasma membrane is called a semi-permeable membrane or a selectively permeable membrane because it admits or allows certain materials to enter and exit the cell. As it also limits the movement of some other materials, it is also known as a selectively permeable membrane.
The cell membrane also acts as a structural support system. Different types of plasma membranes exist in different types of cells, and the plasma membrane in general contains a lot of cholesterol as its lipid component, which distinguishes it from other membranes within the cell.
The cell membrane’s chemical nature makes it extremely flexible, making it the ideal border for quickly growing and dividing cells. The membrane, on the other hand, is a powerful barrier that allows some dissolved chemicals, or solutes, to pass through while preventing others. Small molecules and lipid-soluble molecules can pass through the membrane, but the lipid bilayer efficiently repels the numerous big, water-soluble molecules and electrically charged ions that the cell needs to survive.
