Amino acids are the organic compounds that make up proteins. Proteins are the building components of all living cells. All amino acids are made of the same fundamental elements: carbon, hydrogen, oxygen, nitrogen and sometimes sulfur. The basic atomic structure of an amino acid is shown in the picture above. There are nearly 80 amino acids that exist in nature, but only 20 of these amino acids are used by the human body to make proteins.
The human body is able to produce only 12 of the 20 amino acids it needs to survive, according to Dr Elson Haas, author of "Staying Healthy with Nutrition." The eight amino acids that cannot be produced by the body, called essential amino acids, must be obtained in the diet. Amino acids are not stored in the body so if these essential amino acids are not provided in the diet the body will become protein deficient.
All proteins are composed of chains of amino acids. The sequence and type of amino acids in a protein determine a protein's function. Proteins are vital for every biological function and therefore amino acids are equally important. Proteins are made continuously in the body, and the body has a constant need for amino acids to create these proteins. Amino acids are also found free in the body, functioning mostly as chemical messengers.
The structure of an amino acid is a carbon atom bound to a hydrogen atom, an amino group (NH2), a carboxyl group (COOH) and any variety of side chains, termed an R-group. This R-group can vary greatly between amino acids. It is this R-group portion of the amino acid that determines the chemical properties of an amino acid. This R-group can be as simple as the hydrogen atom in glycine or as complex as the aromatic ring found in tyrosine.
If the eight essential amino acids are not consumed in sufficient quantities, the body is unable to produce protein. As a result of this deficiency the body may not be able to utilize non-essential amino acids and these amino acids are excreted by the body in the form of urea and creatinine. Amino acid deficiencies are more likely to occur in individuals with severe malnourishment, nutritional absorbency issues or restricted diets such as vegetarianism.
There are many diseases that can result if there is an error in the amino acid sequence. Sickle cell anemia, for example, occurs from an error in the amino acid sequence of the hemoglobin molecule. This error causes hemoglobin molecules, which carry oxygen in the blood, to become deformed and block blood vessels. Other diseases, such as phenylktonuria and maple syrup urine disease, result from the body's inability to metabolize amino acids.