Question

Who proposed the sandwich model of the plasma membrane?
A. Davson and Danielli
B. Robertson
C. Singer and Nicolson
D. Benson

Answer 1

Hint: The sandwich model of the plasma membrane was proposed in 1935. It is also known as the pauci molecular model.

Complete answer:
The Davson-Danielli model or pauci molecular model was a model of the plasma membrane of a cell, proposed in 1936 by Hugh Davson and James Danielli. It was also called a sandwich model of plasma membrane because the lipid bilayer was coated with proteins on its either side

Additional Information:
- In 1935, Davson and Danielli proposed that biological membranes are made up of lipid bilayers that are coated on both sides with thin sheets of proteins and they simplified their model into the “pauci-molecular” theory.
-The theory declared that all biological membranes have lipid centers (hydrophobic zone) surrounded by mono-layers of lipids that are converted by protein mono-layers (hydrophilic zone).
-They threw new light on the understanding of cell membranes, by stressing the important role played by proteins in biological membranes.
-Cell membranes are mainly composed of two layers of lipids and proteins. The most abundant type of lipid found in the cell membrane is the phospholipids
-The plasma membrane has important functions including, identification, communication, regulation of solute exchange through the membrane, and isolation of the cytoplasm from the external environment.
So, the correct answer is ‘Davson and Danielli’.

Note: There were certain complications in the Davson and Danielle model leading to new research in membrane organization. This research results in the proposal of the fluid mosaic model in 1972 by Singer and Nicolson, which is the dominant model now. It has two key features – a mosaic of proteins embedded in the membrane, and the membrane being a fluid bilayer of lipids. This model agrees with previous models but views proteins as globular entities embedded in the layer instead of thin sheets on the surface.