Which type of molecules primarily compose the cell membrane?

The cell membrane is primarily composed of phospholipids and proteins, which contribute to its structure and functionality. Phospholipids form a bilayer that acts as a barrier, providing a semi-permeable interface between the interior of the cell and its external environment. This bilayer arrangement allows certain molecules to pass while keeping others out, maintaining cellular integrity.

Proteins embedded within this phospholipid bilayer play crucial roles in various functions, including transport, signaling, and structural support. These proteins can be classified as integral or peripheral, depending on their location and interaction with the membrane. Integral proteins span the membrane and can facilitate the movement of substances across it or act as receptors for signaling molecules.

This combination of phospholipids and proteins is essential for the membrane's flexibility and fluidity, allowing cells to adapt to changes in their environment while providing a controlled system for regulating biochemical processes. Other choices, while related to cellular composition, do not accurately describe the primary components of the cell membrane.