The fluid mosaic model was proposed by S.J. Singer and Garth L. Nicolson. This model explains the structure of the plasma membrane of animal cells as a mosaic of components such as phospholipids, proteins, cholesterol, and carbohydrates. These components give a fluid character to the membranes. Components of plasma membranes are
- Cholesterol – It is located between the phospholipids and phospholipid bilayers. It helps the plasma membrane to retain the fluidity and prevents the compaction of hydrophilic tails at low temperatures and their expansion at high temperatures.
Phospholipids – Phospholipids are the main fabric of the plasma membrane. amphipathic molecules with a hydrophilic head and a hydrophobic tail and attached to a glycerol molecule by a covalent bond.
- Proteins – The plasma membrane has three types of proteins they are
(1) Integral Proteins: These proteins form channels to allow the movement of large molecules and ions across the hydrophobic layer of the membrane.
(2) Peripheral Proteins: These are found embedded in a single leaflet of the membrane. They carry signals from one segment of the membrane and relay it to the another.
(3) Glycoproteins: They stabilize the membrane and are responsible for intercellular communication.
- Carbohydrates – These are attached to proteins on the outside membrane layer.