Proteins are the major structural material of animal tissue. Fibrous protein molecules are long, spiral chains that are folded to form strong structures such as hair, fingernails and muscle tissue.
In addition to this, proteins play an important role in the maintenance and regulation of life processes.
These globular proteins have the spiral chains folded into spherical shapes and are responsible for substances in the human body such as haemoglobin, enzymes and certain hormones like insulin.
Proteins are natural condensation polymers formed by joining together thousands of amino acid molecules.
Amino acid molecules have two functional groups - the amine group (-NH2) and a carboxyl group (-COOH).
Proteins are formed in a condensation reaction when amino acid molecules join together and a water molecule is removed.
The new bond formed in protein molecules where amino acids have joined (-CONH) is called an amide link or a peptide link.