Question

Membranes are complex structures composed of

(A). RNA
(B). Proteins
(C). Lipids
(D). Carbohydrates

Choose the correct answer from the options given below:

• A. (A), (B) and (C) only.
• B. (A), (B) and (D) only.
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

Biological membranes follow the lipid-protein-carbohydrate mosaic composition.
Nucleic acids (like RNA or DNA) are never structural components of cell membranes.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Biological membranes define cell boundaries and organize intracellular compartments. Their biochemical composition dictates their selective permeability and structural fluidity.

Step 2: Detailed Explanation:
Biological membranes are primarily composed of:
- Lipids (C): Form the double-layered sheet (lipid bilayer), mainly consisting of phospholipids, cholesterol, and glycolipids.
- Proteins (B): Embedded as integral or peripheral proteins, serving as channels, receptors, and enzymes.
- Carbohydrates (D): Covalently attached to proteins (glycoproteins) or lipids (glycolipids) on the outer membrane surface, acting in cell-cell recognition.
Membranes do not contain RNA (A) as a structural component.
Therefore, membranes are composed of (B), (C), and (D).

Step 3: Final Answer:
The correct option is 4, which corresponds to (B), (C) and (D) only.