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Osmosis

Standard Level

Cell Membranes Phospholipids Membrane Proteins Glycosylation Fluid-Mosaic Model Types of Transport Simple Diffusion Osmosis Facilitated Diffusion Active Transport

Standard Level

Higher Level

Membrane Fluidity Cholesterol Vesicular Transport Ion Channels Carrier Proteins Cell Adhesion

B2.1.5
Movement of water molecules across membranes by osmosis and the role of aquaporins

Osmosis is the net movement of water molecules across a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration (until equilibrium is reached)

While water is moving to a more concentrated solution, osmosis is still a passive process as there are less free water molecules when solute levels are higher (so water is still moving along the water gradient)

Cell membranes also possess integral proteins called aquaporins that function as water channels within the bilayer

Aquaporins facilitate a much faster rate of water transport in response to solute concentrations and their levels can be regulated to help control the osmotic conditions of a cell

Osmosis

Cell Membranes Phospholipids Membrane Proteins Glycosylation Fluid-Mosaic Model Types of Transport Simple Diffusion Osmosis Facilitated Diffusion Active Transport Membrane Fluidity Cholesterol Vesicular Transport Ion Channels Antiporters Cotransporters Cell Adhesion