Building block of protein

Amino acid is the basic building block of proteins; when linked together, amino acids form specific proteins. There are more than 50 known amino acids, but only 20 are used in making proteins and only 9 are considered essential.

Amino Acids.

The basic building block of a protein is called an amino acid. There are 20 amino acids in the proteins you eat and in the proteins within your body, and they link together to form large protein molecules.