Question

Why is the cell membrane called the fluid mosaic?

Answer 1

Hint: Fluid mosaic model is also explained as quasi fluid in which proteins are embedded in the lipid bilayer. The cell membrane consists of various molecules which float along with all the lipids in the membrane.

Complete Answer:
Plasma membrane is also called the cell membrane. Fluid mosaic model of plasma membrane:
The fluid mosaic model of the plasma membrane was proposed by S.J. Singer and Garth L. Nicolson in 1972.
The plasma membrane contains the components like phospholipids, cholesterol, proteins, and carbohydrates
These all components of the plasma membrane give the membrane a fluid character.
The proportions of the components of the plasma membrane that are proteins, carbohydrates, lipids vary with the cell type.

Components of the plasma membrane:
There are the three components of the plasma membrane:
A. Phospholipids
B. Proteins
C. Carbohydrates

1. Phospholipids:
Phospholipids are the class of lipids that are present in the plasma membrane. A phospholipid is a molecule that consists of glycerol, two fatty acids, and one phosphate-linked head group. They are amphoteric in nature which means that they have a polar or hydrophilic head and a no-polar or hydrophobic tail. Phospholipids arrange themselves in a manner that their hydrophobic tails face each other and hydrophobic heads face out.
2. Proteins:
The proteins are completely embedded into the membrane structure with their hydrophobic membrane regions interacting with the hydrophobic regions of the phospholipid bilayer.
3. Carbohydrates:
Carbohydrates are always found on the exterior surface of the cells where they are bound either to proteins (forming glycoproteins) or lipids (forming glycolipids). A plasma membrane is a semi-permeable membrane which means that it allows the movement of selective molecules or ions across itself.

Note:
According to the fluid mosaic model of the cell membrane, it has a quasi fluid structure in which lipids and proteins are arranged in a mosaic manner. Fluidity is important for various membrane functions. Phospholipids and many intrinsic proteins are amphipathic, that is they possess both hydrophilic and hydrophobic groups.