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Regina Bailey

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By Regina Bailey, About.com Guide to Biology

What are Lipids?

Friday August 1, 2008
Most people think of lipids negatively because they associate them with fats. Although some lipids are classified as fats, lipids are not "bad." On the contrary, they provide very important functions in the body.

Lipids are diverse compounds that are grouped together because they are insoluble in water, but soluble in nonpolar solvents such as ether. Common lipid types include fats, phospholipids, and steroids. These lipids have various functions in the body.

Fats are composed of fatty acids and glycerol. They store energy, help to insulate the body, and cushion and protect organs. Phospholipids contain two fatty acids and are a major component of cell membranes. Steroids are cholesterol derived hormones that regulate various physiological functions in the body.

Comments

August 2, 2008 at 10:49 pm
(1) David says:

Is the strict definition of a lipid any compound that is insoluble in water, but soluble in nonpolar solvents? I.e., any compound that behaves this way would be called a lipid regardless of any other characteristics?

August 8, 2008 at 6:45 pm
(2) biology says:

No, this is not a strict definition. Lipids are naturally occurring organic compounds. They can also be soluble in fats, other lipids, or oils.

August 10, 2008 at 12:33 pm
(3) afash says:

steroids are noy only hormones but also vitamin like vitamin -D

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