What is the primary structural feature of the plasma cell membrane?

• A. Triglyceride bilayer
• B. Protein core
• C. Phospholipid bilayer
• D. Carbohydrate matrix

Answer: (C)

The primary structural feature of the plasma cell membrane is the phospholipid bilayer. This bilayer consists of two layers of phospholipid molecules, each containing a hydrophilic (water-attracting) "head" and two hydrophobic (water-repelling) "tails." This arrangement creates a barrier that is fluid, allowing proteins and other molecules to move laterally within the membrane while also maintaining a distinct internal environment for the cell.

The phospholipid bilayer is crucial for the membrane's function, as it regulates what enters and exits the cell, helping to maintain homeostasis. Additionally, the fluid nature of the bilayer is essential for the mobility of membrane proteins, which are involved in various functions such as signal transduction, transport, and cell recognition.

Other options do not accurately depict the primary structural feature of the plasma membrane. For instance, triglyceride bilayers do not exist in biological membranes; triglycerides are primarily used for energy storage and are not a structural component of cell membranes. A protein core does not describe the overarching structure and would refer more to specific proteins rather than the membrane as a whole. A carbohydrate matrix also misrepresents the composition of the plasma membrane; while carbohydrates do play roles in cellular recognition and