Amino acid
Any of a class of 20 molecules that are combined to form proteins in living things. The sequence of amino acids in a protein and hence protein function are determined by the genetic code.
2. The building blocks of proteins. These are coded for within the DNA.
3. Any of a family of subunits that are joined covalently to produce polypeptides.
4. The unit molecular building block of proteins, which are chains of amino acids in a certain sequence. There are 20 main amino acids in the proteins of living things, and the properties of a protein are determined by its particular amino acid sequence.
5. Any of the subunits that are polymerized to form proteins.