What is the role of proteins in the cell?

Proteins are molecules made of amino acids. They are encoded by our genes and form the basis of living tissues. They also play a central role in biological processes. For example, proteins catalyze reactions in our bodies, carry molecules like oxygen, and carry messages from cell to cell.
The biological properties of a protein molecule depend on its physical interaction with other molecules. In this way, antibodies are attached to bacteria or viruses in order to mark them for destruction. Hexokinase binds ATP and glucose to catalyze the reaction between them, actin molecules bind to each other to assemble into actin filaments, and so on.