None of the above.
A protein is a large complex molecule made up of smaller units called amino acids which are attached to one another forming long chains or polymers.
Amino acids are the building blocks of protein but they are not proteins themselves.
During digestion, proteins are broken down right into their monomer units, and these are amino acids. The sequence of amino acids determines each protein's unique 3 -dimensional structure and its specific function.
Proteins do most of the work in cells and are required for structure and function of cells.
