Question

What are the components of the cell membrane?

Answer 1

Cell membrane:

1. It is a dynamic fluid-structure.
2. It is selectively permeable i.e. only some solutes are allowed to enter the cell while the other solutes are not allowed to enter.
3. In the plasma membrane proteins are inserted into the lipid bilayer.
4. The proteins are arranged in a mosaic arrangement throughout the lipid bilayer.

Lipid bilayer:

1. The lipid bilayers are composed of two leaflets of amphipathic lipid molecules.
2. The polar head groups of the amphipathic molecules face the aqueous phase while the non-polar tails face the hydrophobic interior of the cell membrane.
3. There are three classes of lipids in the bilayer namely- phospholipids, glycolipids, and sterol.

Peripheral proteins:

1. These proteins are bound to the membrane by electrostatic and hydrogen bonds.
2. These can be extracted from the membrane by mild ionic treatments or by changes in pH.

Integral membrane proteins:

1. They are bound tightly to the membrane.
2. They have transmembrane proteins that have non-polar side chains that interact with the hydrophobic fatty acyl chains of the phospholipid bilayer.
3. They cannot be extracted by gentle procedures and can be extracted only by strong treatment like detergent treatment.