cellular membrane

 From Patton KT, Thibodeau GA: Anatomy and physiology, ed 9, St Louis, 2016, Mosby.) 600 471 600 471 79 62

The plasma membrane is made of a bilayer of phospholipid molecules arranged with their nonpolar “tails” pointing toward each other. Cholesterol molecules help stabilize the flexible bilayer structure to prevent breakage. Protein molecules and protein-hybrid molecules may be found on the outer or inner surface of the bilayer—or extending all the way through the membrane.

Cellular Membrane The cellular membrane is the most important component of the cell, contributing to protection, communication, and the passage of substances into and out of the cell. The cell membrane itself consists of a bilayer of phospholipids with proteins, cholesterol, and glycoproteins peppered throughout. Because phospholipids are amphipathic molecules, this bilayer creates a hydrophobic region between the two layers of lipids, making it selectively permeable. Many of the proteins, which pass completely through the membrane, act as transport highways for molecular movement into and out of the cell. Figure 5-4 illustrates the structure of the cellular membrane. FIGURE 5-4

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