1. Education
You can opt-out at any time. Please refer to our privacy policy for contact information.

Discuss in my forum

Cell Membrane - A Cell Biology Definition

By

Cell Membrane

Cell Membrane

Credit: Mariana Ruiz Villarreal
Definition: The cell membrane is a thin semi-permeable membrane that surrounds the cytoplasm of a cell, enclosing its contents. Its function is to protect the integrity of the interior of the cell by allowing certain substances into the cell, while keeping other substances out. It also serves as a base of attachment for the cytoskeleton in some organisms and the cell wall in others. Thus the cell membrane also serves to help support the cell and help maintain its shape.

The cell membrane is primarily composed of a mix of proteins and lipids. While lipids help to give membranes their flexibility, proteins monitor and maintain the cell's chemical climate and assist in the transfer of molecules across the membrane.

Phospholipids are a major component of cell membranes. They form a lipid bilayer in which their hydrophillic (attracted to water) head areas spontaneously arrange to face the aqueous cytosol and the extracellular fluid, while their hydrophobic (repelled by water) tail areas face away from the cytosol and extracellular fluid. The lipid bilayer is semi-permeable, allowing only certain molecules to diffuse across the membrane.
  1. About.com
  2. Education
  3. Biology
  4. Biology Dictionary
  5. Cell Membrane - A Cell Biology Definition

©2014 About.com. All rights reserved.