Question

Who proposed the Fluid mosaic model of the plasma membrane and when? Describe the fluid mosaic model of the plasma membrane with the help of the diagram.

Answer 1

Hint: The cell has various layers which will provide them protection, fluidity and elasticity. The cell components can be mobile due to these layers, they do not let the cell sap to elucidate. They form a rigid outer wall/membrane protecting it from the exterior tensions.

Complete answer:

Plasma membrane is the cell membrane that separates the interior and exterior components of the cell from the surroundings. The cell wall is on the outer side of the plasma membrane.
The fluid mosaic model was proposed by Singer and Nicolson in 1972, to explain the structure of the plasma membrane. It was based on the thermodynamic principles of organization of membrane lipids and proteins. It also gives evidence of lateral motility in the membrane matrix.
According to the Fluid mosaic model, there is a lipid bilayer having proteins embedded in them. This bilayer provides elasticity and fluidity to the membrane. It restricts the lateral diffusion of membrane components because it has the two-dimensional liquid. There is little amount of carbohydrates in this layer.
The bilayer has phospholipids, proteins, cholesterol and carbohydrates. It is the most accepted model depicting the differentiation of the cell from the exterior.
The previous models given were the Robertson Unit membrane model and Davson-Danielli tri-layer Model. They were having some objections so this model was proposed. The fluidity of membrane was determined by x-ray diffraction and calorimetry. This showed that the integral proteins diffuse at rates which are affected by the viscosity of the bilayer.

Note: Plasma membrane has a width of about 5-10 mm. It is named so because the movement of mosaic molecules make the layer impossible to penetrate. The different molecules are scattered in the bilayer. A phospholipid is the main structural component of the bilayer.