One of several types of biological lipid molecules. A fat molecule usually contains a glycerol connected through an ester linkage to three fatty acid chains (triglyceride). When these are digested by the body (hydrolyzed), they break down into glycerol and a fatty acid.

Fatty acids have an even number of carbons in the chains. Some of the chains are all single bonds, therefore called saturated fatty acids. Those with double bonds are known as unsaturated fatty acids. Because addition of a double bond causes a kink in the chain, unsaturated fatty acids dont stack well together and have lower melting points (tend to be liquid at room temperature). Fatty acids that have long chains or are saturated tend to have much higher melting temperatures and will be solid at room temperature. Saturated fatty acids are more unhealthy than unsaturated ones because they are readily converted into the steroid cholesterol, contributing to cardiovascular disease.

Fatty acids act as energy stores and are stored in special cells in the body known as adipose cells. Because triglycerides are not very soluble in water, they tend to pack together, allowing a cell to store large amounts in a small area. Additionally, they are a richer source of energy and one 1g of a triglyceride will usually yield as much energy as two or three grams of carbohydrate.

See also: phospholipid lipid bilayer detergent micelle

Fatty acids

  • Seldom found not as part of another molecule
  • Consist of chains containing an even number of carbon atoms, normally between fourteen and twenty-two.
  • About 70 different fatty acids are known
    • Differ in chain length
    • Differ in whether the chain contains any double bonds or not
    • Differ in the position of any double bonds
  • A fatty acid, such as stearic acid, in which there are no double bonds is saturated because bonding possibilities are fulfilled.
  • A fatty acid, such as oleic acid, thgat contains carbon atoms joined by double bonds is unsaturated because carbon atoms have the potential to form additional bonds with other atoms.
  • Unsaturated fats (tend to be oily) are more common in plants than in animals, saturated fats have higher melting temperatures.

Fatty acids are any of many long lipid-carboxylic acid chains found in fats, oils, and as a component of phospholipids and glycolipids in animal cell membranes.

When insulin levels are too low or there is not enough glucose in the blood to use for energy, the human body burns fatty acids for energy. This causes ketone bodies to be created as waste products, and they can cause the acid level in the blood to become too high. This in turn may lead to ketoacidosis, a serious illness.

From the BioTech Dictionary at For further information see the BioTech homenode.

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