Question

For years, scientists have known that the major components of the plasma membrane were lipids and proteins. Which model best describes the molecular makeup of the plasma membrane?
A) It is a static mosaic model, with embedded proteins within the phospholipids, but the proteins do not move.
B) It is a fluid mosaic model, with proteins interspaced in the phospholipids, both of which can freely move laterally.
C) It is a sandwich model, with phospholipids on the inner and outer portion of the membrane and proteins in the interior.
D) It is a bilayer model, with phospholipids oriented to the exterior of the cell and proteins oriented to the interior of the cell.

Answer 1

B) It is a fluid mosaic model, with proteins interspaced in the phospholipids, both of which can freely move laterally.

Explanation:

The fluid mosaic model proposed by Singer and Nicolson describes the plasma membrane’s structure as a mosaic pattern of components consisting of phospholipids, proteins, cholesterol, and carbohydrates; all of which provides the unique fluid character of the membrane.  

According to this model, the phospholipids constitute the main fabric, cholesterol attaches between the phospholipids in between the layers, integral proteins embedded within the bilayers of the phospholipids, peripheral proteins along the peripheries of the layers and carbohydrates outside the membranous layers.