essential amino acid

essential amino acid

n.

An alpha-amino acid that is required for protein synthesis but cannot be synthesized by humans and must be obtained in the diet.

---

essential amino acid

Etymology: L, essentia, quality

an organic compound not synthesized in the body that is essential for protein synthesis in adults and optimal growth in infants and children. Adults require isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Infants need these amino acids plus arginine and histidine. Cysteine and tyrosine are derived from methionine and phenylalanine, respectively, and are considered semiessential. See also amino acid, nonessential amino acid.

---

amino acid,

n an organic acid in which one of the CH hydrogen atoms has been replaced by NH₂. Amino acids are the building blocks of proteins.

amino acid, essential,

n the group of amino acids that cannot be synthesized by the organism but are required by the organism. They must be supplied by the diet. Isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine are essential for adults; these eight plus arginine and histidine are considered essential for infants and children.

amino acid, glucogenic

n the group of amino acids that produce enzymes that may be converted to glucose if necessary.

amino acid, ketogenic

n an amino acid that produces ketone bodies following chemical alteration of its carbon skeleton.

amino acid, nonessential,

n the group of amino acids that can be synthesized by the organism and are not required in the diet.

amino acid pool,

n an accumulation of amino acids in the liver and blood that adjusts to meet the body's need for protein and amino acids.