Question

What is true for plasma membrane?
a. It is symmetrical due to presence of glycol-calyx at inside only
b. Lipids show flip flop movement
c. Extrinsic proteins are more abundant on outer surface
d. Percentage of the carbohydrates is more than proteins

Answer 1

Hint: Plasma membrane is a lipid bilayer membrane. Membranes have different compositions. It shows the trans-bilayer motion. Intrinsic proteins are present in large numbers. Carrier proteins are present in it that helps in transfer of molecules in the membrane.

Complete answer:
Plasma membrane is the cellular membrane. It consists of both lipids and proteins. It is the phospholipid bi-layer. It is a semi-permeable membrane. A stable barrier between two aqueous compartments is present in it. These compartments are present inside and outside of the cell. In this layer, carrier proteins are present which carry out specific functions of the plasma membrane, including selective transport of molecules and cell-cell recognition.

It shows flip-flop movement which is called trans-bilayer motion. It is asymmetric because of the presence of different composition on different sides of the membrane and asymmetrically distribution of phospholipids. It contains two types of proteins: intrinsic and extrinsic proteins. The abundance of them is intrinsic proteins. Only 5-10 percent of carbohydrates and 52 percent of proteins are present in it.

From the above information we have found that lipids show flip-flop movement.
Hence, the correct answer is option (B).

Note: Membrane also contains glycolipids and cholesterol. Glycolipids are mostly found in the outer leaflet of the plasma membrane with their carbohydrate portions. The structure of phospholipids is responsible for the basic function of the membrane between two aqueous compartments. Inner chain is hydrophobic and contains fatty acid chains. Cholesterol prevents the membranes from freezing and maintains the membrane fluidity.