According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly

a. spread in a continuous layer over the inner and outer surfaces of the membrane.

b. confined to the hydrophobic interior of the membrane.

c. embedded in a lipid bilayer.

d. randomly oriented in the membrane, with no fixed insideoutside polarity

Embedded in a lipid bilayer. (Ans. C)

Explanation:

Fluid mosaic model explains different observations such as the structure of functional cell membranes. According to this model, there is a thin polar membrane composed of a two-layer of lipid molecules called lipid bi-layer or phospholipid bi-layer in which proteins molecules are embedded. This layer provides fluidity and elasticity to the membrane structure.

These membranes form a continuous barrier around all cells and they are a flat sheet in structure. The lipid bilayer is working as a barrier that keeps proteins, ions and other molecules where they are needed to be and preventing diffusing them to other areas. They are impermeable to most hydrophilic molecules. They are particularly impermeable to ions, which allow cells to regulate pH and salt concentration in membrane through the transport ions across their membranes using proteins knows as ion pumps.