Differences Between Osmosis And Facilitated Diffusion

In the body of an organism, molecules or ions move from one place to another by physiological processes. The main physiological processes are diffusion, osmosis and active transport. In the case of osmosis and facilitated diffusion; they have some similarities as well as some differences. Osmosis is the spontaneous movement of water molecules across a semi permeable membrane from a region of high concentration of solution to a region of high solute concentration. Facilitated diffusion on the other hand is the process of spontaneous passive transport of molecules across a biological membrane via specific trans-membrane integral proteins. Some of the differences between osmosis and facilitated diffusion are:

1. Type of molecules

Osmosis involves the movement of water molecules. Water molecules move from a region of high concentration to a region of low concentration. Facilitated diffusion on the other side involves insoluble compounds such as sugars, amino acids and ions which can pass through a partially permeable membrane.

2. Concentration gradient

Concentration gradient is the number of molecules within a particular area. It could also be taken as the gradual difference in solute concentration between two areas. The process of osmosis causes the molecules to move down a concentration gradient. This means that an osmotic pressure must be created so that solvent molecules move from a region of low solute concentration to a region of high solute concentration. Facilitated diffusion on the other hand causes molecules to go from a high concentration to a low concentration gradient. This brings in a difference between the two.

3. Presence of a membrane

A membrane is a flexible enclosing or separating tissue forming a plane or film and separating two environments usually in living organisms. When it comes to osmosis; a membrane is essential I order to create a concentration gradient between two different environments. Facilitated diffusion on the other case can take place either in the presence or absence of a membrane. This is because molecules can move freely from the area of high concentration to that of low molecule concentration.

4. Carriers requirement

 Biologically a carrier is a protein in the membrane that aids the movement of molecules or ions from one region to another. Facilitated diffusion requires carriers in the movement of molecules. The molecules bind to membrane-spanning transport protein and together move form towards the region of low concentration. In the case of osmosis, a carrier is not required in the movement of the water molecules. This highlights a noticeable difference between osmosis and facilitated diffusion.

5. Water molecules

 Osmosis involves movement of water molecules across a semi permeable membrane. This means that water is an essential for the process of osmosis to take place. On the other side; facilitated diffusion does not require water molecules for other molecules to transfer. A major difference can be noted that osmosis requires water molecules but facilitated diffusion does not require any water molecules.

6. Process of occurrences

The process is how physiological means take place. Osmosis occurs when the medium surrounding the cell has a higher water concentration than the cell. The cell gains water molecules due to the osmotic pressure effect. Osmosis also occurs when water moves from one cell to another. Facilitated diffusion on the other hand occurs when the medium surrounding the cell is in high concentration of ions or molecules than the environment within the cell. The molecules move from the surrounding medium into the cell due to diffusion gradient.

From the differences highlighted above it is clear and evident that osmosis and facilitated diffusion differ in one way or another.

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