Protein is used by our bodies in a number of different ways. It's used to break down our food, fend off disease, build muscle, and heal from wounds. You see, protein can fill many roles within the body. It functions as an enzyme--a molecule that assists in chemical reactions (like digestion)--to break down food or fight disease. Protein can also form your muscles, which is why protein is vital to healing and growing. Even the billions of cells that you're made of contain membranes built with protein. Without protein, human life would not be possible.
Protein is key to such reactions as metabolism, DNA replication and molecule transportation. They are also key in making sure the human body reacts properly to stimuli. Proteins do not exist for extended periods of time, which is why they need to constantly be recreated and taken in as part of a balanced diet. The proteins eventually degrade or are exported out of the cells. If the human body did not get enough protein then it would not be able to replicate DNA, which means that the body would not be able to heal itself, reproduce or grow as needed. Each protein has a unique amino acid sequence, which is given to it by the gene that encodes it. These sequences help determine what the protein will be used for inside the body. The protein that is not ingested through diet is synthesized through the process of translation.