fluidmosaic

The fluid mosaic model describes the structure of cell membranes. It proposes that the cell membrane is a dynamic and complex structure, not a static barrier. The term "fluid" refers to the ability of membrane components to move laterally. Phospholipids, the main building blocks of the membrane, are arranged in a bilayer and can drift and rotate. This fluidity is crucial for many membrane functions.

The "mosaic" aspect refers to the arrangement of proteins embedded within or attached to this phospholipid bilayer. These proteins are diverse and perform various roles, including transport of substances across the membrane, enzymatic activity, signal transduction, cell-cell recognition, and attachment to the cytoskeleton and extracellular matrix. Some proteins are integral, spanning the entire membrane, while others are peripheral, associated with the surface. Carbohydrates are also present, typically attached to lipids (glycolipids) or proteins (glycoproteins) on the outer surface of the plasma membrane, playing roles in cell recognition. The model emphasizes that the membrane is not a fixed structure but a fluid assembly of phospholipids, proteins, and carbohydrates.