Question

What is the role of proteins and lipids in the plasma membrane?
A. They provide flexibility to the plasma membrane
B. They provide impermeability to the plasma membrane
C. They provide porosity to the plasma membrane
D. They provide softness to the plasma membrane

Answer 1

Hint: Plasma membrane is the lipid bilayer membrane. It consists of lipids and proteins. Lipid is the non-soluble part, it acts as a barrier. Protein channels present in the membrane allows the entry and exit of specific molecules.

Complete answer:
Cell membranes are also called plasma membranes found in all the cells. It separates the outer matter from the inner matter of the cell. It is the lipid bilayer. It is made up of lipids and proteins. It contains the two ends hydrophilic and hydrophobic. It is a semi-permeable membrane. It allows the entry of only specific materials inside the cells. The main function of the lipid in the membrane is to form permeability barriers of the cells. Subcellular organelles are present in the form of a lipid bilayer. They also play an important role in cellular processes. Low molecular weight molecular weight molecules make the functions of the membrane more diverse.
Proteins present in the plasma membrane play a very important role in the transfer of molecules. It consists of integral membrane proteins, peripheral membrane proteins and polypeptide toxins. They perform many functions such as: membrane receptors proteins that transfer signals from internal and external environments, transport proteins help to move molecules and ions across the membrane, membrane enzymes have many activities such as oxido-reductases, etc.
Proteins also involve cell adhesion molecules. It allows cells to identify each other and interact. It also involves an immune response.
From the above information we have found that proteins and lipids in the plasma membrane provide impermeability to the plasma membrane.

Hence, the correct answer is option (B).

Note: Globular proteins, fibrous proteins, and disordered proteins are some common membrane proteins. About 4000 proteins of E-coli are verified to be membrane resident. They can target modern medicinal drugs. Diseases such as heart disease, Alzheimer’s and cystic fibrosis can be caused by implication of membrane proteins.