Source: Body Builder, Classroom Clipart

Proteins are long chains of amino acids bonded together. Our body uses amino acids to make specialized proteins that perform specific jobs. Your hair and nails are made of protein. Your muscle tissue and bones contain protein. The hemoglobin, found in your blood, contains protein. The enzymes that are used in digestion are proteins.

There are 21 different amino acids that the human body uses to make specialized proteins. Your body isn’t able to produce nine of the 21 amino acids, so they must be obtained by eating foods rich in protein such as meat, fish, eggs, beans, and dairy products.

The bond between amino acids is called a peptide bond. When there are many amino acids linked together it is called a polypeptide.

Polypeptides must be broken down to individual amino acids in order for the body to use them. The breaking of a peptide bond is a chemical change.

How does the digestive system break down the polypeptides into amino acids?