Certain amino acids are essential for proper functioning of the body and the brain, such as tryptophan found in corn. In addition, proteins are essential as various specific proteins produced as a result of gene expression carry out all general functioning of the body. That is, the genetic pool of the human body that is composed of DNA and its associated genes gives rise to specific proteins that carry out their individual functions. Deficiencies of protein or one or more of the essential amino acids leads to reduced growth in children or loss of muscle mass in adults.