Hydrophobic effect

Hydrophobic Effect is a fundamental principle in the field of biochemistry and molecular biology. It refers to the observed tendency of nonpolar substances to aggregate in aqueous solution and exclude water molecules.

Overview

The hydrophobic effect is primarily due to the disruption of the highly dynamic hydrogen bonds between molecules of liquid water by the nonpolar solute. The introduction of a hydrophobic molecule into water causes the water molecules to rearrange themselves to create a cage-like structure around the molecule. This is known as the "clathrate cage" and results in a decrease in entropy of the system, which is thermodynamically unfavorable.

Role in Biological Systems

The hydrophobic effect plays a crucial role in two fundamental biological processes: the folding of protein molecules into specific three-dimensional shapes, and the formation of cell membranes.

Protein Folding

In proteins, the hydrophobic effect is critical for the correct folding into the native state. The hydrophobic residues of the protein tend to aggregate together to avoid contact with water, while the hydrophilic residues are generally oriented towards the aqueous environment. This process is driven by the hydrophobic effect and results in the complex three-dimensional structures of proteins that are necessary for their biological function.

Membrane Formation

The formation of cell membranes is another biological process that is driven by the hydrophobic effect. Cell membranes are composed of lipid bilayers, with the hydrophilic "heads" of the lipids facing outwards towards the aqueous environment, and the hydrophobic "tails" facing inwards away from the water. This arrangement is energetically favorable and is a direct result of the hydrophobic effect.

See Also

• Hydrophilic
• Lipid Bilayer
• Protein Structure

References

• Water drop on a leaf
  Water drop on a leaf
• 
  Dutch process and natural cocoa
• Liquid water hydrogen bond
  Liquid water hydrogen bond