QS Study

General Functions of Cell Membrane

The thin pliable and elastic semipermeable membrane which envelopes the cell is called cell membrane. It is selectively permeable, which means that it only lets certain molecules enter and exit. It can also control the amount of some substances that go into or out of the cell. Main functions of the cell membrane are to retain the physical reliability of the cell – that is to automatically enclose the filling of the cell and to organize the movement of particles e.g. ions or molecules, into and out of the cell.

General Functions of Cell Membrane

  • Maintain internal environment
  • Maintain exchange of substance between ECF & ICF
  • Give definite cell structure
  • Used for endocytosis.

Special Functions

Functions of cell membrane proteins-

  • Structural proteins: Part and parcel of the membrane structure.
  • Carrier proteins: Take part in facilitated diffusion.
  • Channel proteins: Specific for definite ion.
  • Enzyme proteins: Act as enzymes (i.e. ATPase)
  • Receptor proteins: For binding hormones and neurotransmitters.
  • Glycoprotein: Acts as antigen.
  • Act as a pump: Na+ – K pump.
  • Gives attachment of cytoskeleton.
  • Some of them act as cell adhesion molecules.

Functions of lipid bilayer:

  • Highly permeable to lipid-soluble substances such as O2, CO2, and alcohol.
  • It acts as a major barrier to water-soluble substances such as ions and glucose.

Functions of glycocalyx:

  • The membrane provides the intercellular contact through the glycocalyx.
  • Glycocalyx acts as a receptor substance for binding hormones.
  • It takes part in the immune reaction.

Functions of Cholesterol:

  • Cholesterol of cell membrane helps to determine the degree of permeability.
  • Cholesterol also controls fluidity of the membrane.