The modern understanding of the plasma membrane is referred to as the fluid mosaic model. The plasma membrane is composed of a bilayer of phospholipids, with their hydrophobic, fatty acid tails in contact with each other.

The passive forms of transport, diffusion and osmosis, move materials of small molecular weight across membranes. The landscape of the membrane is studded with proteins, some of which span the membrane.

plasma membrane — composed of a bilayer of phospholipids, with their hydrophobic, fatty acid tails in contact with each other. fluid mosaic model — describes the structure of the plasma membrane as a mosaic of components including phospholipids, cholesterol, proteins, glycoproteins, and glycolipids (sugar chains attached to…. osmosis — transport of water through a semipermeable membrane according to the concentration gradient of water across the membrane that results from the presence of solute that cannot pass…. fluid nature of the membrane — due to temperature, the configuration of the fatty acid tails (some kinked by double bonds), the presence of cholesterol embedded in the membrane, and the mosaic nature o.