Question

Complete the following statement.
In Robertson's model of plasma membrane
A. The only outer layer is opaque
B. Only inner layer opaque
C. The middle layer is transparent
D. The inner layer is transparent

Answer 1

Hint: According to the statements given by the scientist Robertson, a single membrane contains a bimolecular lipid booklet pack in between the outer and inner protein coatings and arranged in a wrinkled layer conformation. It is believed that such a device is the same in all cell membranes. Robertson's model is also known as the single membrane model. Davson Daniell and Robertson proposed this model. When measuring the surface tension on the membrane, this indicates the presence of proteins.

Complete answer: In 1950, J. David Robertson examined cell membranes from electron microscopic images of cut material. Preparations include routine fixation in a solution of osmium tetroxide and potassium permanganate and dehydration in a solvent such as acetone before distribution. In the single membrane model, the protein layers are asymmetrical.
Properties of the membrane according to the unit membrane model:
On the outer surface, it is a mucoprotein, whereas, on the inner surface, it is a protein that is not slimy.
Phospholipids spontaneously form bimolecular systems in vitro when added to aqueous media and do not require surgery to maintain the minimum energy conformation of synthetic membranes.
Hydrocarbons are poor conductors of electricity, so the sustainable hydrocarbon phase of natural membranes would explain the membrane's well-known electrical resistance.
Their solubility can explain the high permeability of natural membranes for non-polar molecules in the non-polar lipid phase and at the same time the relative impermeability to small ions, which are insoluble in this medium, is also taken into account.
  Hence from the above points, it's clear that according to this model, outer and inner layers have proteins, so the correct answer is “Option C”.

Note:
The mitochondrial and plastid membranes show particles in or on them, but the plasma membrane does not look like that. Objections to unit membrane model-The concept of a single membrane requires uniformity of membrane properties. Still, the mitochondrial, endoplasmic reticular and plastid membranes are used by F.S. Sjostrand (1963) distinguishes it from the plasma membrane. The thickness of each membrane may vary due to differences in the thickness of the osmophilic and atmospheric layers. A single membrane appears as a single trilaminar structure in the plasma membrane, endoplasmic reticulum, Golgi complex and lysosomes, but in mitochondria, plastids and nuclei have outer and inner membranes, each with a single membrane structure plan.