Which of the following best describes the structure of biological membranes?

• A. A solid matrix of cholesterol molecules
• B. A single layer of phospholipids with no proteins
• C. A phospholipid bilayer with embedded proteins forming a fluid mosaic
• D. A rigid layer of cellulose fibers

Answer: (C)

Verified step by step guidance

1. Understand the basic structure of biological membranes: Biological membranes are primarily composed of lipids, proteins, and carbohydrates. The lipids form the structural framework, while proteins and carbohydrates contribute to functionality.
2. Learn about the phospholipid bilayer: Phospholipids are amphipathic molecules, meaning they have both hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails. In biological membranes, phospholipids arrange themselves into a bilayer, with the hydrophobic tails facing inward and the hydrophilic heads facing outward.
3. Explore the concept of embedded proteins: Proteins are embedded within the phospholipid bilayer. These proteins can be integral (spanning the bilayer) or peripheral (attached to the surface). They play roles in transport, signaling, and structural support.
4. Understand the fluid mosaic model: The term 'fluid mosaic' describes the dynamic nature of biological membranes. The phospholipid bilayer is fluid, allowing lipids and proteins to move laterally within the membrane. The 'mosaic' refers to the diverse array of proteins and other molecules embedded in the bilayer.
5. Compare the options provided: Evaluate each option against the fluid mosaic model. The correct description is 'A phospholipid bilayer with embedded proteins forming a fluid mosaic,' as it accurately reflects the structure and dynamic nature of biological membranes.