Essay by PaperNerd ContributorCollege, Undergraduate February 2002

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Tryptophan is an essential amino acid. There are 20 common amino acids, eight of them are essential, while the other twelve are non-essential. The difference between essential and non-essential amino acids is that non-essential amino acids are naturally produced by the body, where as the essentials are not. These must be obtained from the diet.

In food, tryptophan is the least abundant amino acid. However, the richest dietary sources of tryptophan include bananas, dried dates, milk, cottage cheese, meat, fish, turkey, and peanuts. One particularly popular source of tryptophan is turkey. Since increased levels of tryptophan stimulate the production of serotonin, which increases sleepiness, people tend to be tired after eating large amounts of it.

There is no official recommended dietary allowance for tryptophan. The estimated adult daily requirement is less than 1.5 milligrams per pound of body weight. Infants require 7 times that amount; children need less than 2 milligrams per pound.

Amino acids bond with each other through condensation reactions. (ETC) Amino acids exist in two isomers. They have either left or right-handed forms, and are named L and D, respectively. Organisms can only synthesize the L form. The D form tends to have no function in most cases.

Each amino acid contains an identical backbone, which is made up of a carbon chain, as well as amine and carboxyl functional groups. Amino acids differ in their unique side chains. They can be made up of anything from a single hydrogen atom, to a complex 10-carbon molecule.

Tryptophan is unique in that its side chain is also the center of the serotonin molecule. Serotonin is a neurotransmitter. This means that it regulates the transmission of nerve impulses in the brain. In the brain, tryptophan is converted to 5-hydroxytryptophan (5-HTP). This...