The fluid mosaic model describes the cell membrane as composed of which two primary components?
- A.Carbohydrates and proteins
- B.Phospholipids and proteins
- C.Cholesterol and nucleic acids
- D.Glycolipids and carbohydrates only
Show answer & rationale
Correct answer
B. Phospholipids and proteins
Rationale
B is correct: The fluid mosaic model (Singer & Nicolson, 1972) describes the cell membrane as a dynamic phospholipid bilayer with embedded and peripheral proteins. The phospholipids form the structural matrix ('fluid'); the proteins float within it ('mosaic'). Cholesterol is also present and modulates fluidity, but the two primary components are phospholipids and proteins. A is incorrect: Carbohydrates are present on the outer surface (as glycoproteins and glycolipids) but are not the primary structural components alongside proteins. C is incorrect: Cholesterol is a component but is not paired with nucleic acids. D is incorrect: Glycolipids and carbohydrates alone do not define the primary composition described by the fluid mosaic model.
Key concepts