Phospholipids

Phospholipids are a class of lipids that are a major component of all cell membranes. They can form lipid bilayers because of their amphiphilic characteristic. The structure of the phospholipid molecule generally consists of two hydrophobic fatty acid "tails" and a hydrophilic "head" consisting of a phosphate group. The two components are joined together by a glycerol molecule. The phosphate groups can be modified with simple organic molecules such as choline.

Structure

The 'head' of a phospholipid is made from a glycerol molecule. To the glycerol backbone is attached two fatty acid chains, which are 'tails', and a phosphate-containing group, which is the 'head'. The phosphate group is modified by an alcohol. Phospholipid molecules have a hydrophilic head that is attracted to water, and one, or two, hydrophobic tails that repel water.

Function

Phospholipids form the main structure of all cellular membranes. This includes the outer layer of the cell itself, and the membranes that enclose all of the cell's organelles. They are also involved in metabolism, signal induction, and as a raw material for the production of other molecules.

Types of Phospholipids

There are four major types of phospholipids found in the plasma membranes of cells. They are Phosphatidylcholine (PC), Phosphatidylethanolamine (PE), Phosphatidylserine (PS), and Phosphatidylinositol (PI).

See also

• Lipid bilayer
• Cell membrane
• Lipid
• Fatty acid
• Glycerol
• Phosphate
• Choline
• Phosphatidylcholine
• Phosphatidylethanolamine
• Phosphatidylserine
• Phosphatidylinositol

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